[Edit: Yeah, I see the original post date now.]
I'm currently playing with
Macaroon! and
Macaroon: Extras.
I believe the default install leaves the Blizzard bars in place, though if it's not the default there is a check box option in the configuration panel to toggle the Blizzard bars on or off.
Macaroon! lets you create macro bars. They work like regular button bars in most instances, i.e., you can just create bar(s) and drag spells, potions, etc. to them and it just works. The bars and buttons have a variety of configuration options (size, scale, # of buttons, type of bar/button, bar shapes like arc, linear, etc.). Bottom line is that it appears as a fully-customizable bar addOn - but they're completely separate and distinct from the Blizzard bars so you do not have to replace the Blizzard bars with them at all if you don't wish to do that.