In my 30 gallon, I've had two diamond gobies, both of which had carpet surfed within the first few days of having them. But I've had my yellow watchman for at least 10 months, and he's really cool. Right now, he's made his cave under the RBTA rock, and claims that corner of the tank as his.
In my 75 gallon, the only fish that I have in there so far is a gold headed sleeper goby, which is pretty cool. Spends most of his day sifting through the sand, which helps it stay clean, but also gets sand on top of the rocks and corals, so I have to occassionally take a turkey baster to them. I've been happy with both, and would recommend either.