A sunny slope says alpines to me, but your idea sounds good too.
Don't forget wildflowers can fill a spot until other things fill it in.
Caroline

My Iris do really well on my south facing slope. Most of the summer, it's dry, and they almost never get any shade. I have them stationed on the outside of my fence, next to the posts. In the fall, after they are done blooming... I try to divide them up, so eventually every fence post should have its own clump of Iris.

Also on my south facing slope, with NO SHADE - ever...the lilacs (surprisingly) bloom consistently every spring. Even despite the occasional spring frosts that can take them off guard. My Sage, Catnip, and Thyme do okay there too... with the bonus that the smell really good. For later blooms in the summer...black-eyed susan's always show up. Same with the California poppies, sedums, pansy's - many of those plants can reseed themselves every year.

I get 320 days of sunshine anually...but at this altitude, that sunshine is potent. Often, plants that typically thrive in full sun will FRY on my south facing slope. Even the grass dies if it gets too dry in the summer. Finding things that can survive there can be a challenge...but anything drought tolerant has the best odds.

Other than that... adding a new layer of compost to the entire slope every year has worked wonders. Besides that, everything growing on my south slope gets surrounded by a fast draining mulch too... (except the pine trees, and in some cases...spaces where I'm intentionally trying to encourage erosion, etc.) Without that protective layer of mulch, whatever bare soil does not erode away by August... takes on the consistency of hard baked pottery, which is no fun to work with.

Just some ideas...

Leslie