Schooling fish are tougher than most people are willing to aclowledge. At least in person, I have yet to see anything but solo schooling fish work out in a reef in the long term. All seem to have the schooling behavior that dictates a "low man" who receives all the hostilities. Having no place to run, he eventually succumbs to the stress. The remaining school proceeds to select a new "low man"....repeat until you have a solo act. If there were tiny schooling species such as you'd find in freshwater, I think our experiences would maybe be different. With the fish available, there's just no way for someone at home to keep anything close to a sustainably sized school of dozens or more individuals.
On the experimental side, Klein's Butterflyfish (a slight risk in a coral tank, but I personally know several people who keep them) seem to be strong schoolers and at least in my experience don't seem to subscribe to the behavior noted above. Definitely do some more web searching on your own before deciding on any of the fish that have been suggested so far. IMO, the cardinals are the best-suited for your tank of all those, but also the most boring (to many people they look like freshwater fish).
As a more off-the-wall suggestion, how about a crew of Barnacle Blennies? While not schooling, they are social and very entertaining to observe. I've seen them blended into reefs from 20 gal up to 250 gal and they're still cool.
-Matt