gobies are great! I have a yellow watchman goby, and i love him. They're bottom dwellers, and they like to hang out in the caves of the LR, so you may not see him that much, but they're cool nevertheless.
NO DRAGONET OF ANY KIND!!! This includes the "scooter blenny" which is not acutally a blenny. These fish live off of copods, and die after a few months. Unless you have a refugium, and 100+ lbs of LR, don't do it. They seldomly take to frozen foods, and aren't hardy at all.
another fish i really enjoy is the firefish. They're beautiful, and are schooling fish, so you can keep a few in the tank. I'd have some if my tank weren't already stocked to the max...
Sorry to bust your bubble about the mandarin dragonet... There's plenty of other amazing fish you can have.
I have this in my tank:
1 clownfish
1 yellow watchman goby
2 lawnmower blennies
1 engineer goby aka convict blenny (it's neither a blenny or a goby... wonder why it's name that)
1 black & white heniochus (this is a butterflyfish, and they require a 100+ gallon tank... didn't know that when i got him, and the LFS said "oh sure, he'll do great in a 55g tank..." last time i listen to them...)
1 cleaner shrimp (the life of the tank!!! I love my cleaner shrimp, and plan on getting one or two more... they like to be in groups... He cleans my hand whenever i put it in the tank. It's hard for me to keep my tank clean because he jumps on my hand as soon as i put it in the water).
jenn