I had chiclids and bred them for years and I loved them. They really are awesome, pretty fish. They are not expensive to keep, and most are pretty hardy. Dave is right, except after dealing with them, I can say the plants may be a problem! They like to move substrate, big fish will even move large pebbles the size of dimes around- a territorial thing. I have a friend who can't keep the plastic plants from floating! As far as rocks, they really don't care, I had both smooth and slate in my tanks, whatever looks natural. Driftwood is awesome in the tank, it's pretty, and it helps stabilizes ph. I used large pebble like gravel, not sand because they have the habit of sucking it in and blowing substrate back out. I always felt that would keep the tank cloudy, although, I know some people use sand. I like it because I was able to get the small gravel and large pebbles cleaner since you can vacuum it a lot easier and thoroughly. Python and others make the syphon cleaning systems that clean gravel and they sell gravel tubes from 20" to 72" long.
I think some different very colorful malawi chilids would be awesome in a 275g tank! My LFS has a wall that has to be 12-15ft x 20 ft long filled with african chilids and it looks awesome!
Just be careful to read up on the species that you might like. They are territoral and some are very aggressive. Last lesson you need is how easy it is to lose an expensive fish. I had fish jump into a breeder net at the top of the tank to kill another. He actually had to go airborne to get into the net but there was no stopping him. That's how strong their insticts are! Also, be careful of the more delicate ones that require more care. I love my sw tanks but if I had the room I would have both a very large sw and a very large chiclid tank!
Edit: Oh yeah, Dave is right about the lights too. As a matter of fact, I don't think they like high lighting. I you have T5's already, just don't use all of the bulbs in your fixture. Actually, T8's are perfect for them.
