ground cover for the flower garden

by Julie
(Highland, Illinois)

I was considering replacing the mulch in my full-sun flower garden with a ground cover, I am concerned about it choking out other plants. Is there a suitable ground cover that will still allow planting of both annuals and perennials, or should I just keep mulching?
I am in zone 6.

Doug says that if this were his garden, he'd keep mulching. The deal with ground covers is not that they'll choke out other plants (although some will) but that they invade other plants, making dividing and digging a monstrous chore.

And they do funky things like climb up the perennial to share the sunlight (not killing but not helping the garden design either).

Plus ground covers are invasive so if you plant them in a perennial garden, you won't control them very well because you'll always be whacking your perennials when you want to whack a ground cover.

Mulch.