I think Petco has been getting more interesting fish lately. They have started stocking Dempseys, convicts, green terrors, puffer fish, pictus, and the like. Nothing truly rare but more interesting than their standard fare. I got my GT there and its a happy, healthy growing specimen. My convicts I got there too and they are gorgeous.
Unfortunately the Petco by me can never keep ich out of their tanks and most of the time the fish are infested.