My firefish tends to hang out smack in the middle of the tank. If it get spooked it zips behind the rocks and pops its head out once in a while, but for the most part it kind of hovers around out in the open. Gobies tend to stick to the bottom of the tank, in crevices and caves and such. Clownfish are always a good time. They're, well, clowns. :x
Jawfish are really interesting, you just need a deep (4-6") substrate so they can burrown properly. For the most part they just kind of hover right at the mouth of their cave, so not a fish you're likely to see zipping all over the tank.
I've never had a nano, but most that I've seen usually contain some manner of cleanup crew. A few hermits, some snails, maybe a sally lightfoot crab or emerald crab would suffice. The only other thing you have to really keep an eye on, once the tank is established, is salinity, because with such a small amount of tank volume, a small amount ov evaporation can throw your params out of whack fairly quickly.