Mated Pair-Which one?

Hello, I currently have a 26g bowfront aquarium. I have a 2.5 inch Clarkii Clown, and a 1.5(ish) inch Yellowtail Damsel. The two fish get along quite well (except at feeding time). The next fish I would like to get would be a mated pair. I understand that 4 fish would be a lot of work, but I would really love to have some sort of mated pair. What do you think are the best mated pairs, and what do you think are a kind of mated pair that I could find at the lfs or liveaquaria?

Thanks...