A swale was put in behind my property and the developer blew some sort of grass seed w/fertilizer all over every surface to stabilize the raw soil. It's quite tall stuff with wider blades than fescue. I planted shrub roses at the top of the swale after pulling up grass and putting down 4+ inches of mulch. The grass keeps running rhizomes up and over into the bed and I haven't found a way to totally keep the grass out.

What ground covers may work for me? The area gets both sun and part-sun exposures.

A gc I have that is tougher than grass is ground cover Comfrey, Symphytum grandiflorum. I haven't tried it under roses, just under fruit trees. It gets around 6-12" tall. Vinca major once established is tougher than most grasses, though some can seed into it. It gets rather tall, though. Most of my other good gc lets grass grow up through it, so it's really hard to get rid of the grass- Vinca minor, Rubus calycinoides, Arctostaphylos uva-ursi, etc. Mulching really deeply to partially smother the grass and partially make it easier to pull out might help.