DMD,
I'd agree with Betty in that they're not really a "wet pet" personality, but I love watching my 3 groups of Mbuna in a 75G. They're a bit like watching the gorilla or monkey exhibits at the zoo. Definite interaction and body language, and what appears to be a pretty complex hierarchy and social interaction. They're always busy excavating sand and while they don't school, they're constantly moving and cruising in and out of the rocks and caves (and holes they've dug under the rocks).
I wonder if you'd like a Tanganyikan community tank in that bowfront? I'm considering one for a 40B that I have in the garage for a summer project. Cichlid forum also has a nice Tang section. User "Razzo" there is probably the most knowledgeable on Frontosa (though I suspect he'll tell you that they like colonies and aren't suitable for your 72G). I'd consider putting two rockpiles in that tank, separated by a sand bed with escargot shells, then put 6 Calvus or comps (one rockdweller), 6 Julies or Caudopunctatus (second rockdweller) and then 6 Neolamprologus Multifascitus (multies) or Lamprologus Occelatus (shelldwellers). Cyprichromis would be the top dwelling dither from the Lake, but they're crazy expensive and hard to come by (and sort of look like your rainbows, I guess). Using rainbows or danios as a non-Lake T dither is often suggested, as long as the water parameters match.
The real point seems to be that the Tang fish seem to have lots of character, though admittedly mostly with each other. Seems like you might have the wet pet covered with your pearsei and with Scruffy. Maybe it won't scratch the itch, but it would be a nice complement to your other tanks, imho.
P.S. If you've not already done it,
www.cichlid-forum.com is a pretty solid community. A much broader set of experienced moderators than what you find on the puffer forum, but a lot of thoughtful and like minded fish keeper mods who will happily engage and help you sort out any questions you might have, though like usual, we might not always like or agree with the answers, ymmv! Good luck, and I'll definitely be watching with interest to see what you put in that bowfront!