Here's my on preferences in terms of needed UI tweaks, in no particular order. I suggest most these be options, so players can decide for themselves.
1. Ability to sort Exchange by price.
2. Removal of quest hints from the radar (NPC markers), or possibly the ability to hide the radar altogether (for challenge)
3. Option to import/export UI layout, keymap and chat tabs from character to character.
4. Removal of the shield damage display rings from around the ship model (Its already displayed on the HUD.)
5. Option for a secondary target for buffing/healing purposes. Currently it's quite frustrating to be required to clear your target before you use certain abilities (engineering, science team etc), otherwise they will buff the target of your target rather than you.
6. Being able to sort the skill trainer window by Class, ground or space.
7. Addition of the 11 and 12 boxes ( - and = keys) for the ability bars.
8. Conversation windows minimize when combat starts.