First, congratulations on finding a tulip that reliably comes back for you--enough that you have to divide them, anyway. What kind are they? To answer your question can you tell us a little bit more about the conditions of your bed? I assume it's full sun?

I have Blue Caesar Irises that get along very well with my tulips. They bloom shortly after the tulips finish, and they have very full foliage that lasts for the rest of the summer.

I plant begonias in my bulb beds, in May for summer blooming, and then pansies in the fall. The pansies come back in the spring, with the bulbs and put on quite a nice show.