Answer: Morning glories are scrambling vines which need to be replanted every year and while they do bloom, the blooms are only open for part of the day. Ivy (Hedera helix) is an evergreen, perennial vine which attaches by little "sticky" airial rootlets. This would probably be the better choice as it is the more adaptable of the two. It would also in time make a solid cover. However, it does not bloom.
I am not sure how "rocky" this slope is, but if there are spots of soil you might try some of the following flowering plants and see which ones do well and then plant them extensively: creeping thyme, creeping sedum, creeping phlox, nepeta (catmint), and yarrow.
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