jeanbean, I don't know much about wild tulips but I would imagine they are spring flowers. To get some color all summer, you could try some stella d'oro daylillies:
They're perennial, bloom all summer long and maintain a compact habit. I have them in with some dwarf blue fescue (about 12-15" high, compact, and stays blue-green all winter, too).
Maybe some nice rocks mixed in, too. Will think some more and get back if I can think of any more flower ideas.