One word of advice: Just because you have space, doesn't mean you have to fill it all. A lower bioload can go a long way to keeping a successful tank, especially in the under 30g category. This mostly applies to fish.
Tailspot blennies are super awesome, as are Midas... though I'm not sure your tank would give enough space for a midas. Do some reading.
I echo the scarlet hermits. They're champs. I would nix the turbos. I always wished they had bigger mouths so that I would have something to punch every time they bulldozed my frags and popped corals off the rocks. I'd go with a strawberry top snail over the turbos any day.
Get a conch for your sand. It will quickly become your favourite critter.
Make a bit of a cave on your drop off face and get some overhang loving fish like blue or yellow assessors (they swim upside down!) or a royal or black cap gramma. You'll get more natural behaviours out of these fish with the right aquascape.
Stay away from any fish that needs a lot of swimming space as you don't really have it.
Wrasses stick to the rocks and some will mow down on your bristle worms. Read up on them.
Cleaner shrimp won't do much cleaning (they get lazy over time because they eat the food you feed the tank) but are super awesome. Get a pair and they'll have babies regularly. They also love overhangs and caves!
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