Lillies are a great choice, particularly if you are ordering them, as they are planted as bulbs in the fall, and so are efficient to ship. Plus they smell fantastic. I love my lilies.
For the front part:
I'm also becoming quite a fan of geraniums (i.e. these things: https://garden.org/plants/brow...
not the annuals your grandmother might have grown). They have a nice habit, leaves that will contrast nicely with your lilies, and bloom well at different times of year depending on which species you choose.
Siberian iris only bloom in spring, but are another thing that is easy to ship, and fit in to a mixed bed much more nicely than the more famous tall bearded iris.
Daylilies bloom summer, also ship well.
Baptisia is a medium-tall plant with a bit of a different look that I like so far.
Aquilegia always does well for me. Comes in lots of colors, can take a fair amount of shade if that's an issue, and you can start it from seed and save shipping.
Centaurea montana grows well here. Seeds around a little and the hummers like it - though it does get scraggly in summer after it blooms.
Tall garden phlox is always a nice choice for summer flowers.
Monarda (bee balm) blooms summer, good for wildlife. More modern varieties may have less mildew problems.
There are anemones that bloom in fall: https://garden.org/learn/artic...
be careful to get one that blooms relatively early. Mine is always getting frosted and dying right as the flowers are about to open.
Sorry I don't have much advice on the back layer - grasses aren't really to my taste and for some reason butterfly bushes don't do well here. If it were my yard, I would probably put in lilacs or old garden roses.
If you want to fill space this year while perennials fill in, it's not too late to plant summer bulbs like dahlia
and gladious, or even some seeds like cosmos or cleome (I love cleome)