Popcorn Lover wrote:

Well I heard that ivy puts down really deep roots and is good for
erosion control on slopes, and we have slopes and a long
embankment in our yard and really need that.

I was also reading something about english ivy being "evergreen
in zones 5 up, but that doesn't make sense, I've never seen it
green in the winter here in Denver.

Vinca minor is another quick-spreading possibility that is readily
available just about anywhere. Is this a shady location? Ivy and vinca
do well in shade. If you've got more sun, creeping phlox will fill in
nicely and does well on slopes.