the light. If you can use window treatments to control the light you will be fine. If not you'll have to weight the advantages of having a bright picture during the day (which an LCD can easily do) with the needs of a great picture at night (which is what plasma excels at).
I decided to go the LCD route because daylight viewing was a requirement in my household. I know my night time picture isn't as perfect as a plasma but its still pretty darn good. If I move to another house I'll reassess the situation but for the time being this setup works great.
We're slugging through the many makes/models/feature sets of the various manufacturers of HDTV's. Wondered what the consensus is on purchasing a 58" plasma in a somewhat bright room. We're also considering 2D versus 3D due to the quickly changing technology and the fact that there is little out there which is actually 3D.