This is not a bad thread to start with: https://www.gardenweb.com/discussions/6208289/best-newish-plants-perennials-annuals-in-your-garden-2021-or-20#n=44

Pay attention to posts from FrozeBud and Mazerolm....both live in chilly zones similar to yours.

Do you have height parameters you would like keep within? There is so much you can grow but off the top of my head these are 3 that I can't do without because of their extremely long bloom time. Read that as all summer. Nepeta 'Walker's Low', Helenium 'Moerheim Beauty' ( I have others that have a short bloom time) and Coreopsis 'Sunray'. I have a miniature Daylily that reblooms pretty much all summer and it is 'Penny's Worth'. I will think of more.

Most have seasonal blooming such as Iris, Peony, Rudbeckia, Allium, Veronica........

ETA - Happy to here you say foliage is important also. Silver can be introduced with most Artemisia, Burgundy foliage with some of the darker leaved Sedum. Variegated foliage with some of the Euphorbia polychromata such as E. 'First Blush'. Ornamental grasses can add movement and texture.

Ooh, new garden beds, that’s exciting!! :)

Here are my top plants with long blooming periods:

1- Echinacea: if they do well in your area, look for long blooming varieties. I've planted 6-7 varieties, and so far my favorite is Bright Star. It blooms for 2 months!

2- Penstemon: I have 2 varieties that are equally gorgeous: Dakota Burgundy and Onyx and Pearls. Dakota Burgundy was planted 3 years ago. They are long blooming, the bloom stalks and foliage are beautiful as well. And when the snow melts, the foliage still looks fresh!

3- Nepeta: I have 4 varieties, my favorite one (by far) is Dropmore. It looks good in fall even after a hard frost.

4- Delphiniums: if you don't mind staking them, they're a lovely addition. They bloom for a long time and if you cut them back, you'll get more blooms, even with our short summers!

5- Tall phlox: they’re beautiful and they smell great! :)

6- Achillea: I love these. I’ve had Terracotta for a few years and I added 2 more varieties in 2021. They were still blooming at the end of September.

7- Veronicas: I planted White Wands 3 years ago and love it. It does bloom again if you cut them after the first blooms are done.

8- Coreopsis Moonbeam: love the soft yellow, and it blooms much earlier than my other varieties.

And here’s my list of top plants for striking blooms that reliably come back:

1- Darwin tulips: if you’re in a deer-free area, you gotta try these. I planted the first ones 7-8 years ago, and they’ve always come back. I read that they must be planted deeply, which I did. Nothing beats tulips after a long winter.

2- Peonies: itohs and herbaceous. They are new to my garden, except for Bowl of Beauty, but one of Canada's largest grower is very close to where I live, they grow both itohs and herbaceous so you'll be ok.

3- Iris: Bearded and Siberian. My favorite Siberian is Pink Parfait, it has a longer bloom period than my other siberian. It's too hard to pick a favorite tall bearded, but Don't Stop Believing was a show-stopper.

4- Clematis: I can never get them to look as good as what other people post online (mine look sparse in comparison), but still, the blooms are amazing. I go mostly for type 3 clematis, the ones that bloom on new wood. Type 2 are ok, but since they die back to the ground, they never get very tall (max 7 feet).

5- Daylilies: this one is a no-brainer for cold zones. I know many people don’t like them, but maybe it’s the ditch orange daylily that they think of? The foliage stays fresh until late fall here. One of my favorites is an old one, Siloam Double Classic.

6- Lilies: I’m just getting started with lilies. I’ve had Apricot Fudge reliably come back for 5 years, and I’m now looking to add a lot more varieties in 2022.

7- Leucanthemums: I’ve planted a few varieties over the years, they’ve always come back.

8- Liatris: they were among the first perennials I planted. Their bloom period is not super long, but they look SO good with echinaceas!

I think that's all I can think of. There are other plants/shrubs that I really like but they are recent addition in my garden so I won't recommend them until they've been in the ground for a few years.

Hope this helps!!

What are your conditions as far as wind and soil pH? I tend to think of WY as alkaline and constant wind, but I don’t know if that applies to your site.

Someone asked about height, and knowing your preferences would help along with any width constraints, or even if you don’t care.

Are you open to flowering shrubs? if so, I would suggest that you consider Hydrangea paniculata Quickfire or Little Quickfire. Both bloom in my cold zone 5a garden for months, typically early July until hard frost.

Oh thank you for all the thoughtful responses! Sincere thanks, especially mazerolm. This is more than enought to get me started. I can have some tall plants. Why not.

I grow some roses, but that’s it for flowers. Grew some lilies, but am waiting to see if they actually come back. My beds are protected, as I’m located in town and the beds are along the south side of my two story house. I am bringing in lots and lots of good soil to mix in . I have removed a lot of native soil already.