In a small tank like that I would try a pair of tank raised clowns and a nice host anemone as the main inhabitants. Being tank raised they will take to the small size much better than wild caught.
Then fill with a couple coral and dusters.
but the goby/shrimp symbiosis would be neat as well. I would try for some "theme" for the fish inhabitants where there is a lot of interaction between them, such as a pair of clowns or a symbiotic pairing like the goby/shrimp.
As I look at my new 30 gal
, covered in brown uglies, I envision a tank teaming with macro algae, lots of little critters and seahorses.
That is probably a year or two away before the tank itself is ready for that.
Sometimes it's hard to explain to the wife that it's an ongoing process,
not just wham, bam, there's the fish man!