in college, my roommates and I used to build 'tents' inside our living room, and hang out in them all the time. We would leave them up for weeks. We built them so that the t.v. was included inside the tent, and generally strung up christmas lights somewhere inside the tent for ambiance. Awesome.
lots of places are carrying 'tee pees' for kids' rooms these days, but I say:
a. build your own (don't buy one!)
b. they're not just for kids!