How much space do you have to work with? Shape? Looking for a border, mid height, and tall arrangement? Mixture of textures and colors? Groupings of plants with similar water requirements?

Aside from sedums, TB Iris, creeping phlox, and daylilies, I have no experience with any of the other plants mentioned.

A side note --

If by "cherry bells" you mean campanula punctata, please be aware that it spreads VERY rapidly via underground runners, and many people consider it invasive.

I had a piece of it growing in my garden for just a couple of months one year, and I spent the next two years pulling out remnants.

If it's any help, I have a 'rule of thumb' I use when doing the perennial portion of a design, for every 3 plants I plant because I like the flowers, I must plant 1 primarily for foliage traits. You may want to consider adding some additional plants with interesting foliage to liven up the garden. There have been a number of posts about foliage on the Perennials Forum if you need some ideas.

When I say 'foliage interest' I'm primarily talking about the color of the foliage but interesting shape (like the large leaves of Ornamental Rhubarb) can also be a consideration.

I can take up as much or as little space as I want for this bed. Here is a rough photo of the area (sans truck and stump). It is probably 8 to 10 feet deep from the stump to the trees.
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I'm thinking a roughly triangular shape. Thank you Duluthinblomz4

I don't mind a plant taking over BUT I can plant the invasive in their pots if they are next to a more delicate plant. Thank you Deeje

A majority of these plants are "extras" from trades and are new to me as well...

I do have Persicaria microcephala 'Red Dragon that has a nice red foliage. Thank you Bindersbee

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Perrennials are nice, but don't forget to give your garden 'bones'. Evergreens for winter interest and structure. Shrubs and small trees for mid-level height. Perhaps some understory trees behind and under the larger trees in the picture. Serviceberry and Dogwood are favorite candidates. For evergreens, I would suggest some of the dwarf hollies or dwarf hemlock species (keep with the dwarfs, you don't have a huge space here). I have a Picea pungens 'Blue Globe' which will grow to 3x3 foot mound and has shocking powder blue needles. If you're adventuresome, you could try Picea orientalis 'Skylands', which is a narrow, slow growing spruce with yellow-green needles all year round. Quite lovely (see attached pictures). There are many selections - one for just about any situation.
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Regards,
K4

I am in the process of working out a trade for Magnolia and Dogwood cuttings but hesitate to integrate them into this bed for fear that they will eventually outgrow it.

The Blue Globe is a striking shape and the Skylands a beautiful color. They would be a good addition to this layout. Thank you for the suggestions Kaitain4