Hi!
I might be resurrecting an old topic, but I personally wanted to add that I love an AddOn called IceHUD.
Basically it replaces the player and target frames and creates an HUD that is much more comfortable to use, and it's oh so powerful: you can customize its look and feel completely, save different profiles (for different classes), create custom bars and do pretty much everything.
I think it's not up-to-date but it still works perfectly with the current patch (by current I mean on our server, tho I think it works with 3.2 as well).
You might wanna give it a try, it's really something that changes the way you play WoW completely... and in case you're too lazy to configure it, if someone helps me, I would love to upload some custom profiles I have created for different classes (what varies is the threat/aggro bar, target of target bars and some advanced stuff like that) and link them here.
Have fun!