I just read an interesting article that helps gauge which size of HDTV you should consider for your size of the room that you have. Ultimately though, you are the one that decides.  Some want the Wow factor, and some just want background noise.  For the best viewing experience, the rule we use is using a multiplier of 1.5 to 3 times the screen size in inches to match the viewing distance.  For example, if you know the size of the room you already have, where you want to sit, and where your new HDTV should go, then you can figure out the ideal HDTV size you should get.

Minimum size = Viewing distance/3

Maximum size = Viewing distance/1.5

The following table shows the calculations for common viewing distances with recommended size ranges:

Viewing Distance in Feet Viewing Distance in Inces Minimum Size Maximum Size
4 48 19 32
6 72 26 46
8 96 32 63
10 120 40 80
12 144 46 96
14 168 52 112