Platties also stay together pretty well, but I think this is more because they have an orgy 24/7 rather than actual schooling behavior.
What about glass cats, I had 6 and they always schooled and had the coolest look of any schooling fish I have ever seen.
You can't beat a see through fish in my books!
I also keep roseline sharks/denison barbs. They are a larger schooling fish. I have 15 in my 6 foot 150 and they are a large school constantly going back and forth.
Just looked these fish up and they aresound and look great. It says they are slightly aggressive thou. What are yours like with tankmates?