I currently have a 27" IPS (FSM-270YG / 2560x1440) and a 21" LCD (1600x900). I mainly do web development so the 27" will very comfortably fit sublime, terminal and chrome with dev tools. The 21" is my spotify/google/hn monitor.

I used to spread my workspace over two 21" monitors, but now having everything on one large monitor is much more comfortable.