I don't think hostas would be any cheaper- the clumps grow fairly slowly (most of them only make one new 'eye' a year, it can take a decade for a clump to double in size) wheras the ground cover roses tend to root along the way, and the next spring, you can go in with a clipper and heavy gloves, and move those 'new' plants to bare areas.

I think the roses would look wonderful...mowing slopes is a right pain in the butt, isn't it?

I'm not sure what color 'seafoam' is, but you might have some luck with daylillies interplanted with the roses- the 'free' ones are orange (around here we call em 'ditch lillies' because that's where we dug them from) but they come in yellows and bronze and well into the pinks.

everyone else is gonna growl at me, but if you're really in a pinch, and looking for something to stop the erosion in its tracks, GoutWeed might be the way to go- though you can call it 'false dead nettles' since 'gout' is just an ugly word. it's a fast-growing groundcover with green and white striped leaves and a cascading habit and rather inconspicuous yellow flowers right about now. the roses would have no problem cohabitating with it (actually, that's where I first met the plant myself) and it spreads like wildfire...which makes it good for an 'impossible' place, and an invasive monster everywhere else.

Well chinacat I guess 'they' will growl at me too, because I think goutweed - I agree, horrible name - would be a good solution and believe me, here on Long Island it grows almost as you watch it! And it is just so pretty. Ok, Ok I know it's invasive - but isn't that what is wanted in a ground cover in circumstances like Deejavu's?

NOOOOO. Do not plant goutweed. You will have it coming out of your ears.