I think it sounds good
I'm sure one of the gourami freaks around here can suggest some good ones to match the tank. You could probably get a good size neon school in that size of a tank with no real aggressive fish.
Also I've read that silver dollars come in several different species...even though most stores just label them silver dollars. Some get to 6 inches...and other get several inches larger than that, so just make sure you have enough room for them when they get large.