Gary,
I agree with your choices, with one exception. In my opinion, aster doesn't earn a spot in a limited garden because the foliage is so ugly and the bloom time is so short compared to many other plants.
Liatris bulbs are available in the spring from everywhere, and so much easier than growing from seed. Walmart and Lowes sell 20 bulbs for $5, or so, a real bargain.
I have an area near my bee hives where I have planted exactly the plants you name, and literally, they get maybe 2 hours work per year. Russian sage is another plant you might use for full hot sun, and the blue is so pretty with the yellow coreopsis. My bees go crazy over mints and sedum. Mints should be contained to pots. Apple mint seems to be the preferred one for my bees. Zinnias, definitely!!! For early spring pollinators, I would add a swath of muscari, aka grape hyacinth. In that area, I would plant 200 or so and let them spread. The foliage in the summer might even keep out weeds. I think an early blue and yellow iris would be pretty mixed in with the muscari. Alliums are cool plants too, and butterflies love them.
I agree with you on the wildflower mixes. It is very hard to tell which is a desirable plant and which is a weed when they are seedlings. Some of those mixes have plants that can become thuggish if in enriched soil or a protected site.
I have found that native beds are much trickier to plan because many natives have short bloom times and need space to spread. The improved versions of natives, (assuming they are not sterile versions) have worked out better for me on the Russian sage, coreopsis, aster, rudbeckia, gaillardia, liatris and bronze fennel. They bloom longer and have a neater growth habit. Longer bloom period means more opportunities for bees and butterflies to find them! On any of them, if you do take the time to cut off seedheads, you'll get more bloom. I leave the last seed heads on in fall because finches feed from them through the winter. Hope that helps a bit! Post a picture of what you end up with, please!!
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