There are many to be had in the
Compilations and Suites section. Many list in the descriptions what resolutions they work for. Some (
nUI being one of them) will adjust based on the resolution you use.
If your not in to the ones posted you can always start building your own. Here is a short list of addons that will get you started.
Action bars:
Dominos
Bartender4
Macaroon
Plus many more in the
Action Bar Category
Unit Frames:
Stuf
Pitbull
oUF (if you dont mind tinkering with Lua.)
Many other choices available in
Unit Mods category
As for moving elements around there are addons like
Fluid Frames and
Move Anything (though it hasnt been updated in a while.)