A bright room like this and expectations which aren't through the roof lead me to recommend a LCD in this particular location. I'm a big fan of plasmas, but you get high quality overall with a LCD. Not as good as plasma, but a brighter image which will matter in a bright room.
My brother got the 65" VT Panasonic and he definitely has viewing issues in his family room due to the windows. It certainly is a great looking display, but just doesn't have the daytime punch which he would like and is visibly missing.
On the 'cheap' side, Sharps 60" LCD is nice. On the awesome side, Samsung has displays which are great.
You would need to provide the exact size of the opening in your space to enusre that a display will fit. 60" Samsung or 60" Sharp would be my first two choices depending on your budget.