General viewing distance from a 32->40 screen is about 7', I'd guess 14' for 70"+
It's a strange situation, and it makes the cut between monitors and TVs.
The HD feed they need to output has 1080 lines. A monitor, say 20" widescreen, is the ideal standard for it. U get a 22" monitor and it's the same resolution stretched. 24" is the step up of standards to 1900x1200.
Get a 32" HDTV and it's the same resolution stretched again - but it uses 'tech' to mush the stretch. Which is why if u play ur Bluray on ur 20" next to ur 32" HDTV, the monitor plays it how it should be. The HDTV plays it the best it can - which is usually pretty darn good, but varies from manufacturer. U can generally play with each manufacturers settings to make them look better, but they can't reach the same standard.
And ofc HDTVs look better the futher away u stand from them. Up close they 'can' look fugly. Viewing distance for monitors is about 2' I believe.
If u dont view the screens side by side, its hard to appreciate. Colors look different in the main - and u will be supprized how big the difference is. (best to turn the monitor off quick if ur doing it at home b4 u get upset

, then go back to feeling good about it.)
73"+ screens will use the same 'techs' to expand in the same way. Without the 'tech' u could see what would be a pixel on ur monitor as a square the size of ur finger hehe.
In work we/they use 24" monitors as they see the network feed, plus the bars and signal feeds u dont get to see at home. Inherently 20" for the picture and a band for the signals.