For the slopes, I'd say you can't beat periwinkle. It holds the soil from eroding, spreads nicely and looks great all year.

I am also partial to cerastium (Snow in Summer) and iberis (candytuft).

I think I heard chamomile or edelweis can be walked on, but I may have dreamed it.

Never had a bit of luck with thyme, even though I watered it regularly. Bad spot, maybe.

Let us know what you decide.

I keep trying to convince creeping thyme to grow in the bare patches of my "lawn" (over the past 10 years) So far with no luck. I'm always jealous of the huge swaths of the stuff growing in the Thruway divide south of Harriman and on the side of the road (steep slope gravelly looking) along route 23 in Green county. Just a couple of days ago I layed mats (removed from a stone patio..it was uncontrolable) to try again. I guess from all this that the first requirement is good drainage and lots of sun. I think another name for it is "mountain thyme" I'll let you know if it works this time.