I'm looking for a small tree or shrub recommendation for the bed on the side of my driveway. I live in Providence, RI (zone 6, maybe zone 7 since we're in the middle of the heat island that is our city.) The bed is ~2 & 1/2' wide by ~25 feet long, raised, in full sun and has good (perhaps somewhat acid) soil. I'm looking for something that'll give us some privacy from our neighbors: I think that means evergreen or something deciduous with a dense branching structure, and grows to at least 8' (as large as 20'.)
I'd also love something that flowers: Elderberries might work there but I'm not sure if it fits the description (bonus re: this plant, I can make wine from the fruit and, double bonus, it's native to RI.) What I definitely don't like is juniper/arborvitae/hemlock/cypress. As far as I'm concerned those plants just sit there and do nothing. C'mon, do something to entertain me, plant. At least have foliage that changes, or flowers, etc.
It would also be helpful to be able to hedge/train/prune the plant into an upright form so our car can get by.
What would you suggest!?