What to show a beginner At my new job, it's soon going to be my turn for doing night/graveyard shifts for a fair amount of weeks. Perfect excuse to buy a decent beginners telescope to replace the 4.5" 15 y/o Meade that doesn't work anymore with a 10" Dobsonian reflector!
My girlfriend wants to join me (which I'm all for), and having grown up on a (relatively poor) farm, she's never had the pleasure of looking through a telescope. When I asked her what she wanted to look at first, she shrugged and said "I don't know. Show me everything!"
The problem is, the stuff I generally stare at are Nebulae and star clusters (since that's all I really could see), despite knowing that there is so much more out there that are equally enticing to the eye.
So my question is this: For any category of objects, what are the most popular? If you have gone to many star parties, what are the objects people are generally asking to see most of the time? What were the things that when you first saw them through a telescope made you go "Wow!"?
Note: Do understand that the objects generally have to be viewable during Late September (new moon), but having new objects I can show her in the coming months would be awesome as well. I've already told her the journey of the grand tour will probably take 6 months to a year (due to earth rotation and all that,) and will require the joining of us to the local astronomy club.
 A: I often run guided tours of the night sky for beginners. I find that the general public responds best to bright objects, especially the Moon, the planets (especially Jupiter and Saturn), double stars, and open star clusters. The objects that serious amateurs enjoy leave them cold, especially galaxies and nebulae. Most people, without eye training, simply cannot see most galaxies and nebulae. I've also found that children under about 6 years of age simply cannot see anything through a telescope; they don't seem to be capable of placing their eye and holding it in position.
Once people have begun to train their eyes, the best objects by far are the Messier objects.  With only a few exceptions, these represent the brightest and best deep sky objects.
A: Good answers on this page. One more thing to add: get a book called Turn Left At Orion. It shows you where each one of those cool objects is located on the sky, and what time of the year is best to observe it.
http://www.amazon.com/Turn-Left-Orion-Hundred-Telescope/dp/0521781906/
Also, install Stellarium on a laptop, or one of the many apps available on the iPhone (SkySafari, Star Walk, Stellarium, Star Map, Pocket Universe, etc).
The book is better for the fixed objects, the software is better for the planets (and fixed objects too).
While you're at it, you may as well get the Pocket Sky Atlas - it's basically the same stuff like one of those apps, but in dead tree format, which sometimes may be preferable.
http://www.amazon.com/Sky-Telescopes-Pocket-Atlas/dp/1931559317/
A planisphere might come in handy:
http://www.company7.com/books/products/graunplanispheres.html
Finally, if you use a regular flashlight to read the maps, your night vision will get killed every time the bright white light is shining in your eyes; say good bye to faint nebulae and galaxies. Get a red flashlight instead. It could be as simple as a red keychain LED (but even that is usually too bright), or you could improvise something (put a resistor in series with the LED to make it less bright, or paint it with black permanent marker leaving only a small hole), or you could get the real deal:
http://www.company7.com/rigel/products/skylite.html
You don't need all this stuff at once. Start, for example, with the book and the red light. Some software is free.
Finally, word of advice: always find the object by yourself first. Don't try to show a novice an object you haven't located previously. This may save you from some unnecessary embarrassment. :)
A: Consider doing something "useful" with it as well. 
The Galilean moons should be reasonably easy to spot, so I suggest you log their positions night after night (e.g. twice per night, one hour between them; then next night, twice as well, etc), so that your girlfriend can see what real science looks like, why it's hard to get it right the first time, etc. The complicated part will be convincing her of the math behind Kepler's laws of motion, etc; I suggest you leave it out for now. Anyway, you can extract very fun numbers, even if you miss the actual well-known numbers by 10% or 20%. Just do it on the side; try not to take too long with it for each night so it doesn't become boring.
Drawing/measuring is fast, it only takes a couple of minutes to log it on a notebook and you can move on to other objects. The first thing is to measure how long it takes for two or three of the satellites to make a complete orbit around the planet. Then you can see which ones are which. The second exercise (more fun) is to use Kepler's laws of motion (namely the third) to make a broad estimate of Jupiter's mass. You can then compare it to our planet to show how "big" Jupiter is...
Of course, it'd help to have the length of the semi-major axes; you can make it easy on yourself and just measure in units of Jupiter's diameter ($7\times 10^4$km) and pretend someone else measured it by other means (e.g. parallax). Another way would be to wait for Jupiter to cross in front of (or near) a star, time its passage, and use this to estimate the diameter (again using Kepler's third law, this time comparing to Earth's orbit around the Sun).
A: Turning a telescope on the Pleiades and Saturn are breath taking for the new (and not so new!) astronomer.  If that doesn't elicit a response then its probably best to go somewhere warmer...
A: I have operated public observing nights at various universities for eight or ten years. These are the objects that have stood out for me.
Saturn and Jupiter are the "stars" of the night sky. Bar none. Spec. Tac. U. Lar. If you can look at Saturn with nothing between it and your eye besides a few panes of glass, and see it hanging in the sky in all its glory, and NOT want to be an astronomer, there is something deeply wrong with you. You can see both the Galilean moons (good opportunity to give an historical lecture, if you're a yarn-spinner) and the shadows of the Galilean moons pass across the surface of the planet. Some of them are fast enough to change noticeably between the beginning and end of an observing night.
The other inner planets, if up. Lots to talk about with them.
The Moon itself is a "destination", not just an obstacle to observing.
The binary star Albireo (the "head" of Cygnus the Swan) is fairly spectacular if you have developed a sense of what's "normal", because it is one of very few objects in the sky that's multiple colors- i.e., Jupiter is brownish, Mars is red, Saturn yellow, most other things white, but Albireo is bright enough that its member stars are distinctly blue and yellow.
Mizar and Alcor (the middle stars of the Big Dipper's handle) are conceptually neat, if visually dull. Mizar and Alcor are a visual binary, while with a backyard grade telescope Mizar resolves into a binary pair (telescopic binary), and with a spectrograph, you can resolve each of those into pairs of stars themselves (spectroscopic binary). So, in one telescopic view, you get all three kinds of binary stars.
The Christmas Tree Cluster (near a foot of Gemini) really, really looks like one (with an 8-inch refractor, in a fairly light-polluted area), complete with Christmas lights, a star at the top, a trunk, and a smattering of presents underneath.
The Beehive Cluster is pretty spectacular as far as open clusters go. Unusually uniform brightness gives it a real appearance of bees.
If you're ready to propose to your girlfriend, it would be hard to beat the Ring Nebula.
The Messier globular cluster M13 in Hercules is really easy to find. It lies right along one of the lines between the four trapezoid stars.
Orion Nebula.  Talk about the Trapezium and star formation. Cool stuff
Pleiades- Lessons in multiculturalism (Different cultures call it different things), consumerism (Subaru logo), and optometry (How many stars can you see? Good vision, 7, 20-10 vision with experience in night sky observation, 14+)
Uranus- Giggles, and then its historical background.
Constellations and asterisms are a lot of fun too, because the audience can "take them home," that is, enjoy them again on a different night when they aren't being treated to a star party.
Get a green laser pointer. Absolutely indispensable, and also has a HUGE "wow" factor.
EDIT: Oh, and the Andromeda galaxy. The observatory where I did most of my observing was too badly light-polluted to see it very well, but if it's dark enough, it's the farthest object any human being in history has ever seen with his own two eyes. The Double cluster in Perseus is pretty impressive in binoculars, but it's so big you can't really appreciate it in a telescope. It's a good object for a n008 to try for her first solo "spot."
EDIT: This is a fairly comprehensive list, including planets, double stars, open clusters, a globular cluster, a galaxy, and nebulae. That's close to a Noah's Ark of everything you can possibly see with a backyard telescope, if you add transients like comets and satellites, and maybe a few other odds and ends like Ceres (though I've never attempted that myself. Is it actually pragmatically visible?)
A: One answer was accepted already.
So just another hint or recommendation:
The app "Google Sky Map" is  free, easily understood and runs on Android smartphones with GPS, gyroscope and a compass. 
It's pretty cool to have this app as a support when standing next to the telescope. Point it to anywhere in the sky and it will show you constellations, planets and more. It also helps explain what is visible in the general direction of the telescope. 
