I went through and labeled in Paint.NET all the addons and the space they occupy, whether visible or not. This should help people get some ideas from what I've done with my UI. I'll add here that this UI works for all 7 of my toons, 5 of which are dual-specced. These include a pally, a druid, a shaman, and a priest, and a death knight; so it's fairly flexible.
