What do you think about George Mason University?

It all depends on what you want out of a program. GMU has some great stuff going for it. The corridor between Baltimore on the north extreme to Richmond on the southern extreme has a great deal of theatre, an active region is good. Also GMU is paired with the Theatre for the First Amendment. This is a great plus, you will be working wiht union professionals, getting training and guidance from those who have gone through what you are going through and made it to a professional level.
That all being said, I do not know much about the quality of the work done there, or the facutly, but that is always subjective anyway. Best thing to do is visit the campus and talk to the other students, see what they are getting out of the program and what they would suggest.
As a response to the first poster, IU has a wonderful program for grad students, watch out for teh great MFA program schools while looking for undergrad, it usually means alot of opportunities to do very little, the school has to give the MFA candidates first ***** at most roles and opprotunities, thus making the undergrads second class.