How to Help Your Cats Get Along

We've had both of our cats for three years now, and they still don't get along. I don't think there is much that we can do to change them at this point, so we just let it be. I think the biggest issue is that they have two very different personalities. The one is very finicky and doesn't like to be messed around with much at all - she's skittish about everything. The other one is a goofball that likes to play around a lot, and she drives my other cat nuts with her antics.