Schools of fish would generally be tetras, rasboras, rainbowfish, danios, or the like. But, since it's such a big tank, you could do a really nice, big school of tiger barbs instead. I've never really seen a truly big group of tiger barbs in a huge tank, and it must look so different from 6-8 in a 29g tank. Then you could get a few bigger, semi-aggressive fish to go with them or cover the bottom. A 225g should be big enough for a couple of rainbow/red-tailed sharks, because it'd be big enough for multiple bottom territories. Or, a group of clown loaches since the tank is certainly big enough.
A big school of rainbowfish in that size tank would also look really cool, but that would be pretty expensive since a lot of them run around $10 or more per fish.