I've been using Ubuntu for about 1 year as my main development machine at work. Here are a few quick suggestions:
* use Clementine as default audio player (rythmbox rescanning each time was killing me, plus some other annoyances that I can't remember). I tried all of the other players and found Clementine to be just perfect.
* use pidgin as default IM client. I must have SIPE to integrate with Office Communicator and at the time of install this was not working in Empathy.
* Look at what Linux Mint is doing with UI. As soon as I can, I'm switching.
Big pros for mint:
* nice color scheme
* single taskbar (at bottom) = more screen real estate and single point of action for my mouse.
* ability to search programs and anything else that lives under the Mint Menu (this is huge).
* conservative and transparent (with regards to risk) update system. I've had some ups and downs with updating packages and I wonder if the mint ranking system would have prevented that...