Yes, it's not a good idea to cycle the tank with fish, although it is a mistake many have made! I'm in the middle of dealing with it right now, and although the fish are okay, it would be so much less stressful if i just knew they were in a fully cycled tank.
But when the time comes, i would have to agree with Alli that a dwaf gourami is a great choice if you're looking for a single fish. They are beautiful, and mine is very responsive. Without fail, he swims to the front of the tank whenever I come over. They also have an interesting ability to squirt water (like an archer fish) which is really funny. If i put my finger over the water he will squirt it, and if i put it in the tank, he will nibble it like crazy. Corys would be the best for the bottom. I have 2 currently with my dwarf gourami, and because they are the only other fish with him, he occasionally spends time with them on the bottom looking for food. But he is mostly on the top/middle of the tank. Corys are a schooling fish, in the Amazon they are found in schools of hundreds. You definitely need to get more than one for them to be happy, but i agree with everyone else that you don't really need to worry about breeding. If you have a gourami and few cories, I would think someone would make a snack out of the eggs before they develop too far!