If you want a school that is that large of a particular fish, I'd go with just one of the ones mentioned, either the rummynose or harlequins. If you have two schools that large in just a 55 gallon tank, you probably won't see a very defined school. They'll either just mix together or be swimming amongst each other so much you won't get a true schooling effect. Plus you'll want for your angels to be the "showcase" fish, with the other fish as a supporting cast. I don't think anybody else has said this, so I'll say that you should get 3 angels, so that you won't have one dominant one beating up on the other all of the time. And as far as the cories, if you get the pigmy ones, they'll be all over the tank, not just the bottom. So I guess I'd say you should stock like this:
3 Angels
10-15 Rummynose
6 Cories
3 Ottos
2 Rams
If you're getting the ottos to keep algae down, I'd personally say you'd need more than 3 for a 55 gallon tank, so you might just want to skip the cories and go with all ottos. Don't add them until your tank has been running with fish in it for a while and some algae has started though.