Personally I would choose 2 versus 1. I have stuff on both monitors all the time and love that part. I want to go to 3 so it gets even better.
I agree with Robert. I've used two monitors for the last 5 years, and wouldn't want a single one regardless of how wide it is. With that being said, I don't use WPDM, so I don't know how much room that takes up. I do know that the feature tree doesn't take up enough space on mine to be an issue.
I have two 24" monitors. One is straight in front of me that I use for SW, and the second to my right for Windows Explorer, e-mail, etc. I wouldn't want one any larger. In fact, though I've had the 24" for about two years, I'm still not sure if I like it better than the 22" I had before.