Multiple panels may be better for the way you work than one large panel. In general I don't think any programmer should have less than two monitors, ever. Ideally three (for the "center"), and if you're crazy, four.
I can work fine with a single 20" 1600x1200. It's not my dream setup but it's also not hindering me for my work (backend systems).
I've been thinking of going the 19/30/19 route, but I've had a hard time finding an affordable mount that converts that scheme into something I can mount on a single monitor arm.
I'm signed up for a metalworking class in the near future, so maybe I can solve that problem myself :)
I'm used to multiple desktops (gnome 3, gnome before that), and multiple panels turn out to be useless to me. I just can't spread my attention across two monitors, whereas I switch desktops without thinking about it.