Then mix them up a bit more evenly vs. the foreground/background layout and you can imagine what I now have in mind for that corner.
With that in mind I came across this great blog post on Delphiniums, which has this to say about companion plants:
"Where tall delphiniums will not work is in your meadow garden, among the unruly tufts of sedges and grasses, or in some similarly naturalistic setting. In those kinds of gardens they make the surrounding plants look shabby, and they themselves look as though they’re waiting to hook up with some randy sailors on shore leave."
I do not think I will back away from my plans; how could they stand out too much? While I am pretty good at taking advice this is going to be a place where I have to learn first hand.
Perhaps some Coreopsis would work well with the Liatris? I should be able to directly sow Coreopsis seeds here; a 70/30 Liatrias/Coreopsis weighting will be attractive so the yellow does not overwhelm.