This will be my 5th season hosting the Super Bowl, and 4th season with the projector installed. I typically have around 40 guests, which is more than the theater room can handle (probably around 25 including people sitting on the floor/standing/walking around). I have extra chairs set up in the theater room, and then I also have the big screen in the living room as well as an old 27" TV in the garage. That way people are free to roam around the house and mingle without missing any of the game. The kitchen is always full of people, too.
As far as food, I get 10 take-and-bake pizzas from the grocery store pizzeria, and rotate them through the oven as the night goes on. This seems to work easiest for me. I ask guests to bring sides, which usually ends up being cookies, chips, dips, salads, etc. I also have a few ice chests for people to bring their own beers. I usually end the night with more beer than I started with, so that comes out a net win.
The Super Bowl should be a fun, relaxed event for you and for your guests. I find that having additional rooms to watch the game (including the garage) means people find their comfort zone easier. If someone doesn't like a crowd or gets claustrophobic, they usually go outside or into the kitchen. If they want to yell and scream, they go to the theater room!
~Tighr: Not helping the situation since 1983