Cories are great. If you are looking for a single larger fish I really like the Flying Fox. And it actually does okay with cories as well. Or else some of the smaller loaches are great liek the Khulie, Zebra and Yoyo. Get them in at least pairs, 3 would be better but can add a little to the overall tank load.
Shrimp are also a great option, either cherry, ghost or amano. They do a fine job of grabbing bits of leftover food.
Don't forget to feed your bottom feeders with sinking pellets.