I'd consider Cotoneaster dammeri, and specifically the cultivar 'Lowfast'. This is evergreen in our climate, is well adapted to hillsides and slopes, tolerates heavy soils and is virtually maintenance free.

The Hypericum (aaron's beard or st. john's wort) is subject to rust, resulting in discoloration and loss of foliage, and is an extremely aggressive spreader. Unless contained, it will invade lawns or other planting areas. Vinca is not that great in a sunny situation and the planting of either of these IMO will not provide a very pleasing appearance over time.

Plant the cotoneaster 16" on center in a diamond or zig-zag pattern and mulch in between. In two seasons you should have a densely knit planting totally covering the hillside. You will have to do a bit of weeding until the coverage is full, but mulching will help with that, as will making sure that most of the weeds are eliminated before planting.