Looking for a good fish...

After moving my angelfish and silver dollars into their larger home, it looks kinda bare. So I've been considering adding a school of small, colorful fish.

First, the tank.

So i need something small, so they won't crowd the tank when the others get bigger. I'd prefer something schooling and something with some color. I've been looking at Serpae Tetras and Lemon Tetras. Any other suggestions?

And what about another Silver Dollar or two? Fill out that school a bit. Or would that be pushing the stocking limit of the tank?

So far here's the fish load:
3 angelfish
4 silver dollars
2 plecos

75 gallons for a pair of angelfish? Since when? Everything I've ever heard is 10 gallons per angel, minimum of 20 gallons tall. And yes, i know plecos can grow quite large.

I've got a Magnum 350 on there with the twin bio-wheels. I have no problem adding an HOB filter or something if necessary. I've been thinking about it, but didn't know if I'd need it.

Lisa: Silver dollars can get quite large. I've read up to about 6" in diameter or even larger. Mine are about 2" tip-to-tail right now.