I did a brief search looking for a compendium thread but didn't see one. It's early so I apologize if I missed it or if this is redundant.
-Add an option to "Simulate full 16 man group with targets."
It would be nice to preview the UI in a full raid setting without having to find 16 people.
-Add an on-screen 'grid.'
I'm a symmetry nazi.
-The ability to flip the XP bar vertically.
-An option to hide character, target, focus, and target of target portraits.
-An option to detach and freely move buffs and debuffs from character and target frames. Also an option to independently scale them from those said frames.
-Add the abilty to change the color and font size of 'Raid Warning' messages. Being colorblind, I find it hard a lot of times to see the red text against some back grounds. I would personally love to change it to white.