There is a genus of Caribbean dwarf groupers called Serranus which behave very much like groupers but stay small(3-4 inches max). Like groupers they are hardy, intelligent, and easy to keep. Take a look at the Harlequin bass, Lantern bass, or Orangeback bass and see if they interest you.
Myles
If you are looking for "Grouper Grouper"... the Pacific Leopard Grouper or the Atlantic Coney will generally be your best bet. Coneys normally max out around 13" and the Leopard around 9".
Snapper wise, the Lane snapper is one of the smaller snappers...normally maxing out around 16" ... from the Indo pacific, the Blue Line and similar species are your best bet.
Triggers will probably be in the realm of the Picassos and similar.