How far back to sit
That's up to you. You already know where you like to sit in a movie theater. In your home, most likely you'll want the projected image to take up about as much of your view as it does in the theater. Due to reasons I won't get into, you'll probably end up with the screen in your room, taking up a little less of the view than when you are in the theater.
Keep this in mind - a big part of getting immersed into a movie, and the ability to "suspend disbelief" that we get in movie theaters is due to the huge amount of your view that the image takes up. A good chunk of the rest is due to everything else around being dark and therefore "not on your radar". You are looking to be immersed in the movie. The right screen size and seating (and other room conditions) are all part of that immersion.
Sound baby, sound
While the image on the screen is the key, don't skimp too much on the audio. Typically a $499 "Home Theater in a Box" may provide decent sound, and play loud enough, but, boy is it great to have some really good sound. (I'm an old audiophile, and my system is ridiculous, but boy does it make for amazing sound.) Room size and speaker placement come into play in your selection. You don't have to spend a ton of money - a nice $300 - $500 AV receiver can handle your source switching for the projector (cable/satellite box, Blu-ray/DVD player, computer, even a game machine like the PS3). Then pick out a good set of 5.1 (or 7.1) set of speakers/subwoofer. If you are planning a major room changeover, you may well want to have your speakers "in-wall" instead of free standing.
Only as good as the weakest link - Go Blu-Ray
I get so many emails about, "do I really need to get a Blu-ray player" Personally, I always recommend it. The difference betweens standard DVD and Blu-Ray of the same movie is often startling. It's not just the higher resolution and therefore significantly sharper image, but also the production qualities. Almost all Blu-Ray discs have been remastered to deliver a superior picture in terms of color fidelity, dynamics, and everything else. The best source material on standard DVD - such as Lord of the Rings, barely comes close to the most average Blu-ray disc. With players to be found for under $200, go for it. Or, as most people do, buy a Sony PS3 and have a great Blu-Ray player, and a top of the line game machine. The final word - get a Blu-ray player.
Enough. It is not my goal to intimidate you. You will do what you can to get the best viewing experience. If you can't do everything - that's fine - even I can't, and this is how I make my living. Still, even a pretty basic setup, with compromises, is, basically jaw-dropping!
Photos Found In This Projector Report
The vast majority of images in this report, can be clicked on, to open a much larger version in a new window, for closer inspection.
Take the images "with a grain of salt". While many images give you a good relative idea of projector performance, especially those about black levels and shadow detail, they should not be used to determine which projector, for example, has the best color or film-like qualities. There is so much loss in getting the picture off the screen through my Olympus E510 (dSLR), through resizing and format converting (we start with RAW format - roughly 9 megabytes per image, and end up with about 100K (for the large images) jpgs when done). Color depth, dynamic range, and more gets compromised. Then there is other software related aspects, your browser, and, rather significantly, your monitor, which on its best day, isn't remotely capable of faithfully reproducing the full original, even if we could get it to you.
The images are there to support my commentary, to educate you, to give you very useful comparisons (such as black level performance where the images are good guides), and finally, to entertain you. Hey, it's fun looking at many of these images, from major movies, etc.