Check the size chart on this forum a bristletooth tang, or other tangs, that are appropriate for a 120...
a variety of wrasses if you're open top, may want to think about a canopy or cover or something.
sleeper goby (sand sifter), Diamond goby (tends to damage rockwork though), Golden Head goby, well just a variety of gobies. a variety of blennies (Starry blenny,lawnmower, midas, etc.)
I love Marine bettas, but they will eat shrimp, so, if you want tohave shrimp of any type, avoid marine bettas.
Anthias, Just really depends on what you want for fish. liveaquaria has a fairly good encyclopedia of information about fish and whether they're reef safe or not, whether or not you purchase from them doesn't matter, their site is good to see the variety of fish available.
Lots of options!