Voted 7.1 as I've been running 7.1 since 2004, and I am at present happy with it. When I initially made the leap to 7.1 (mainly so I could enjoy games in full 7.1, Half-Life 2 being one of the best options at the time) I was living in a fair sized room that could accommodate. Unfortunately then a couple years later my family and I were forced to move and I ended up with a smaller room. Sure my setup may not be laid out the best (and I know this), but it's passable until I can get a larger room.
One thing I do notice is that all the haters are hatin' because the majority of movies today (sans the few recent exceptions that are Toy Story 3, Tron: Legacy, etc.) are in 5.1, but a sound system doesn't stop at just playing movies. A sound system is also great for games as well, and with the PS3 and a PC I am able to enjoy a large number of games in 7.1. I mean with the PC side you have pretty much every game released from Valve, plus there is other games and you can't forget about those that make use of EAX/OpenAL effects. With the PS3, I know a number of the console exclusives feature full 7.1 surround. So yes while people will say that in terms of movies there is a lacking of genuine 7.1 content (not 5.1 being remastered into 7.1) in terms of games there is plenty of content to go around, and believe me I enjoy it. Plus I just want to add that with games you a great sense of immersion. When the sound is done right in a game I can clearly hear the action from all angles, it's great.
To those who may be wondering, I'm only 23 and again I've been enjoying 7.1 since 2004 right around the time when it was announced that sound card manufacturers and PC game makers were coming together to now offer 7.1 sound.