@Swimpy,
I can just edge to seeing your having a patch of sedum there - if it makes sense with other stuff, which is a little hard for me to envision.
I guess I think it's odd with crabapple.
I know it as going with aloes and native grasses, various succulents.. in, say, san juan capistrano, where I designed a property around all of that. It was ephemeral, the guy who hired me is an architect friend who wanted to try this and this and this and this and then that and that and that and that. (He's ok, architect at play).
I still have an interest in your thinking Prairie Garden, sort of Jens Jensen, as opposed to Japanese, or mixed choices (I don't know if I'm negating past talk, urg, probably am.)
If you look him up, you'll see he was a big promoter of landscape design using natives, and has a subsequent number of detractors and people who revere his work, along with frank lloyd wright, yadda yadda. I couldn't give you a Jensen type palette off the top of my head if I tried, would have to research it, but the idea is not much exotic to your area in planting, or (to me) if it is, that the import makes sense with not only your property but the whole region. Not formal, naturesque. Using local plant material if possible.
This is not a lecture, I've natives in my yard but they lose out in numbers to the non natives that I MUST have, so far, although the natives are gaining.