I bought a 52" Mitsubishi rear projection HD tv a couple of years ago.  It is in a basement room.  If I were to put in a room that has more extra light in it I would go LCD or Plasma.  I should have just put in a projector in the basement room which would have worked real well.

I hear that the plasma's are doing good for not having the burning in effect now - and they are getting cheaper now also.

I would go very big since you will be up to 20 feet away and make sure the viewing angle of the TV will work for you.  Some are hard to see when you are not right in front of them.