iris600

I had posted in the "newbie" forum about fish choices for a ten gallon but have decided to go with a 15 gallon high, or a twenty high (both are 24" long, same height, but the twenty is wider). I will be using the dark eco-complete substrate, with AHL supply lighting (I think I want about 2.5 to 3 watts per gallon), DIY CO2 initially but I am selling some stuff to hopefully get a fullblown CO2 system with a PH monitor.
I will have shrimp for cleaners, and am looking for interesting fish that appeal to me for the tank. I was thinking along the lines of the small rainbows, like celebes, or alternatively a pair of the small south american cichlids (such as apistos or german blue rams). I was particularly smitten by Apisto cacatuoides, with their jaunty manner and wonderfulolor variations. I have been doing some research on Apistos and Rams and was wondering if others could share their experiences with different genus's?
I have been told that even small rainbowfish, such as celebes and blue eyes, require much more space than a 15 gallon. Comments?
Also, any other neat fish good for a smaller aquarium that I should look into? A tetra beyond the ordinary cardinal or serpae? A barb beyond the rosy? Thus far I have had people suggest the likes of endlers, fancy guppies, cherry barbs, sparkling gouramis (which I admittedly don't know much about), and even a shrimp-only tank. I would like to stick to one or two species of fish only.
So, have at it, what have *you** put in similar smaller tanks? What would *you* like to put in your smaller tanks?