I use two HD 21 inch monitors. I got them cheap and they work great. The real pain is when I put a laptop to the side of one of them and i have to move my head beyond say 10 degree's. Any length of time looking at the small screen is a killer.
For some of the systems I have to support at work, they are so old and have no budget for upgrades. It kinda helps having a crappy (not that crap) setup that really matches the vibe so I don't get too down on them. :P