I like the sedge idea, but maybe mix in joe-pye weed for some color and maybe butterfly action and new jersey tea (ceanothua americanus) for a low maintenance shrubbery and more butterflies. The shrubs may need some pruning to stay narrow, but probably a twice-yearly thing, they aren't crazy.

If you like the look of long grass, try a sedge. It's native, looks nice, and you can find a variety that grows in those conditions. If some spreads to the neighbor's yard, it will just get mown down.

Sisyrinchium albidum?

Have you considered rocks?

We have a small strip between our garage and ally that is similar size so we don't have to deal with spread. We have done lots of different flowers from Prairie Moon. We have brown eyed susans, purple prairie clover, partridge pea, smooth asters, pussie toes. Most we just planted so we will see how it looks in a few years when they are all established. So you can go with a mix.

However, if you want to keep things small take a look at Flawn which sells flower lawn replacements. We've had white Dutch clover for a few years in the grass which we love. We're seeding self heal now so we will see how it looks in the spring

Native plants, surround with small rocks, make a garden

That or decrotative rocks.