i find that for my standing desk, because i can stand a bit further away from it, a 40 inch tv works best.
Buhhhhhhhh.. at the desk with the chair a 30 to 36 inch would still work well..
don't worry too much about resolution, Almost nothing is worth seeing in HD except movies and dota/hearthstone
So what I do is run everything in 1280x800 on my 30 inch, and when I'm awtching a movie, i'd hotkey to 2560x1600.