I have a 55gal mixed reef which is somewhat similar. Here is what I have or have thought of...
1 pair clowns (I think designer ocellaris are my faves, but obviously it is subjective, tomatoes/maroons get too big)
Chromis (started with three, down to two, will likely end up with one)
Firefish (I actually just like the regular firefish, not the fancy or purple)
Blenny either midas or lawnmower (you should not have two and Midas is prettier IMO, but lawnmower is downright a beast against the algae... I have a lawnmower)
Dragonet (mandarin or scooter blenny, MUST have good refugium in sump to breed copepods)
Flasher Wrasses (I would keep at least two terminal phase males so they flash each other but not same species. Carpenter and McCosker are very popular)
Kole vs. Tomini Tang (I'd also consider a yellow, but you might get a few that won't like a yellow in anything less than a 90)
Angelfish (just no)
Damsel (just no)
Royal Gramma (excellent personality, I personally don't like their look but I think I'm in the minority)
So there are some suggestions, I've likely missed a few that could fit in the bigger tanks but honestly what mostly fits a 75 fits a 55