Lemon tetras are pretty cool. Their colors never look very good in the store, but mine got really bright yellow once I got them home.
I haven't seen many other things that school as well as tetras and rasboras. Also, you need to get some semi-aggressive fish in there for the schooling fish to stay together. My schooling fish really don't stick together all that much because the only thing I have with them is a gourami and betta that generally ignore them.
As far as numbers, more is always better just because it looks better. You'll probably like one big school better than two small ones. I really don't know how much I believe the minimum numbers for schooling fish, though. People usually say you should get at least 5-6 tetras to keep them from being stressed out, but in my experience you can have 3 tetras with a lot of plants and they will be perfectly happy, but 6 tetras in a bare tank will act stressed.