Running Ubuntu on a regular Dell laptop that is sometimes docked in a dual-monitor setup has been quite frustrating after versions 10 or 11 or so. I've had issues, repeatedly, with either setting up Unity for dual screen, or getting X to work at all. Going back to plain Gnome served as a partial workaround, until I switched to the new laptop - and then I started having issues initializing the screens after logging in (one of the screens would randomly remain blank when going into 1280x1024, I have to repeatedly logout/login to make it work).
Eventually, I gave Kubuntu 13.04 beta a try and, surprise, it works perfectly. No Unity nonsense, X works great.
It's a bit strange switching to KDE now. I've actually used KDE 1.0 back in the day, and Gnome 1.0. I've been a Gnome user most of this time. But now I'm starting to find even plain Gnome quite frustrating.