I have a 24 inch samsung and the size is perfect as a single monitor. I, like many, don't like looking at two or more different screens. The only thing I would be aware of is that unfortunately with my macbook pro the quality of the samsung just doesnt compare to an apple display and i fiddled with the settings for ages. Adjustable height and rotation was really important for me, and the quality is good enough for the cost.
I use three monitors, all 22" 1920x1200. The centre monitor is in the landscape orientation, while the other two are in portrait orientation.<p>I am not sure what to think of the wide screen aspect ratio. In some cases it can be good, though sometimes I think it's just a bit extreme.
I have 3 monitors.<p>Left 22" (landscape) 1680x1050
Center 23" (portrait) 1152x2048
Right 22" (landscape) 1680x1050<p>Pretty happy with my current setup. I have them on monitor arms which is the best thing... ultimate control over placement.
1280x1024 17" monitor. I'd prefer something larger, at least 1080p resolution. I've tried using multiple monitors before, though. Doesn't do much for me, but then I mainly used them for playing video games and chatting on IRC...
22" - 27" with anything larger I seem to only see the corners with one eye or I have to move my head to focus on something which is really annoying, 24" is probably the sweet spot for display to price ratio right now.
15" Laptop (MBP) + 21" LDC @ 1600x1200dpi. I like the 15 inch for the laptop and 19-23 for the external monitor though I don't mind a smaller monitor as long as it can run at 1600x1200 or above.