Raid window goes in the same place as tracking since I never have them both up. Detrimentals are in a small area right above my hotbars (between the player window and the little hotbar), with pet window right above it. Group window is right under the player window, for easy click to cure access. Voice chat list is transparent, just to the left of the map...it only lights up with someone's name when they're speaking. Makes for a pretty clean setup even with lots of windows up, great job with the sizing.
I have a 1440x900 screen, and I play windowed but maximized, so it's easier to switch to Firefox, ACT, Vent, etc. I also left some comments and nitpicks on the UI download page, as I wasn't sure which place was more appropriate to post.