[QUOTE....with Plasmas it's 50", 51", 55" and 59". The 50" & 51" seems to have a better deal cost wise when you look at about $300-400 more for 3-4 inches. We're about 10ft on one couch and about 8.5ft on the other.[/quote]
We sit about 9 ft away from the screen in our "home theater" area: our 720p 50" Pan made for a nice viewing experience, at that distance, with "full screen" programming (that is, 16:9 material).
However, we enjoy watching movies, and most DVDs (SD, HD, or Blu-ray) are Letterboxed, and thus the "active" portion of the screen - that is, the part of the screen is showing MOVIE - is somewhat Less Than 50."
OTOH, our 60" Pan provides more "active" screen area with a 2.35:1 Letterboxed movie than the 50" does when displaying 16:9 material - and when we DO watch a full-screen program on the 60" the screen size is wonderful.
As long, of course, as it is HD: SD Material, blown up to 60" at 9ft, looks distinctly worse than SD Material shown on a 50" screen at the same 9ft...
Pick you poison.