Puffer of some sort? I had a dogface puffer about a foot long many years ago. Great personality, neat fish.
Some of the big Angels would hold their own just fine, and there's some gorgeous ones out there.
A friend has a foot long spiny puffer, a dinner plate sized Koran angel, a pair of big blue tangs, a pair of big foxfaces, and some sort of dottyback that is at least 7" long. Active, attractive tank, with little aggressive behavior displayed... Oh, they'll push each other around some, but no damage is done.
Cleanup crew: Might consider using Urchins to handle the bulk of what you'd normally buy snails for. Many of the kinds of fish you're looking at will make a quick snack out of most snails.