I'd go with some kind of Flasher Wrasse (the Mystery Wrasse was a good idea too)...a dwarf, or even Pygmy Angel (there are several, pick one you like)...a Foxface...some kind of smaller Tang (Kole, Tomini, etc)...maybe some kind of Hawk and a school of Chromis.
Mandarins are beautiful fish, just extremely difficult to keep alive).