Is my room big enough?

There's a school of thought that says any room you can walk into is big enough. A closet with a high shelf for the 17" TV, and a low shelf to sit on, is just fine. (Think of the money you'll save on a remote if you can reach the TV)

There's another school of thought that recommends acoustically that 1500ft^3 is the minimum size. If your room were 8' tall, then it would be 16' x 10' x 8' or 1280ft^3.

Then there's the viewing distance. At 60" diagonal, that's 52" w x 29" h.
1.5 times the width is 6.5' away from the screen. That's as close as you'd want (well, you might get away with 1.33 times the screen width).
Using a equalateral triangle (imaging) with the remaining point 6.5' away from the screen, you'd want your front left/right speakers 7.5' apart. In a 16' long room, this leaves about 9' behind your head for a second row of seats and for sound to travel past you (a good thing -- 11' is better).
Some people consider 8' away from the screen to be the minimum no matter what the screen size, even an old 19" television. If you do that, obviously your equalateral triangle gets larger.

(You might want to double check the minimum distance over at the plasma forum. If you're getting a Pioneer FHD1 you might get away with closer, and if you're getting something low resolution you might have to be further)

I think the size of your room would be just fine. You may be a little tight for a second row of seating depending on type of seats (if that is even your intent). In fact you could easily even do a front projection set up with an 80-92" screen and be quite comfortable.
My situation sounds very much like yours...my room will measure 10'6" wide x 20' when finished (including acoustic treatments). My plan is to do a 92"-100" screen.
This way it will still afford me an area outside of the theater to put in a pool table also.
So I would vote, use the smaller room, get the pool table...win/win situation.

Just my 2 cents.

Allan

Definitely do-able. With great 1080P projectors out (and at excellent prices) you can arguably sit much closer. My first row is around nine feet from a 96" wide (110" diagonal) screen and the image is outstanding with HD. With my previous 720P, however, screen door and less detail was limiting. You may even want to consider the plasma and a pulldown screen w/ projection for a more multi-purpose setup.

it looks plenty big without drywall. should be fine. if it turns out too small, just take the drywall back down. that's my plan.

My room is only 15.5x11 and I think its going to work fine (its not quite done yet ).
I'm doing a projector with a 92" screen, only one row of seating, probably a couch.
If you want to see something small but a lot more finished than mine, see if you can find boomerbrian's thread, his room is only 10x11 or something.

If I remember right, 1.5 or 2:1 is suppose to be a good room size ratio for sound (square is bad) so you should be ok.
I think your speakers should be right at ear level?

its not that size that matters, its what you get to put it in.

or in your case, put in it?

rip it up, if it's new construction, buy your builder lunch one day, have him come over and spraypaint an X on all the non-load bearing walls...

then have fun.