Sleestack - About the only way to go big is to go with projection. You may want to talk to a decent A/V consultant who can help you with some ideas of how to make it all work like a piece of cake.
Rear projection using a front projector can give you a 100"+ image and by using a mirror bounce system may only require a few feet of additional space. The rear projection setup can allow for a lot of ambient light in the room while in use - very cool, and on target with budgeting.
Like a regular TV? - Take a look at getting a serious control system for the setup. Crestron, with handheld or touchpanel remotes make the most complicated systems one button easy.
Don't believe it? Really! It's true. I run a plasma & projector in the same room. About 15 sources available to me. One touch turns it on. What does that mean? It means that it fires up the plasma, turns on the surround system, properly goes to the correct input on the displays, makes sure the right equipment is on, and it starts playing through the speakers just like an everyday TV. Want the projector? One button press 'switch' - and it is done. The plasma turns off, the screen drops from the ceiling, the projector turns on - and goes to the correct input.
Turn it off? Once again - just press the power off button and it all goes away. Add to that multiple audio/video zones in the home speakers everywhere, music everywhere you want it - all from one integrated system that maintains consistency in all locations. Take a look, do some thinking about this type of setup...
My setup:
http://forums.audioholics.com/forums/showthread.php?t=16858