How about Daisies, Coneflower or maybe black eyed susans.I'd be temped to put in some low growing asters(for late color).
A few others include:LadyÂs Mantle, Cranesbill, Daylily, Spiderwort. Remember, don't remove the tulip foliage until it is brown.
Hope this is of some help.
Sandy

If it gets much shade try some Hosta's. They have 1000's of kinds.
Paws

This is a really sunny bed, raised and south-facing, so I'm going to save the hostas for the one that faces it, down by the house.

Sandy, concealing the flower-less tulip-foliage is my primary goal, along with having something besides mulch and stems in a large bed. I love all the perennials you suggested, but I ended up ordering several mum plants last night. I tend to have problems telling the weeds from the flowers if I get too complicated. So we'll see what happens!

Thanks,

Kristi