You have lots of choices in your zone! Just off the top of my head: Calamagrostis eg Karl Foerster, Overdam, Eldorado; Panicum eg Shenendoah, Heavy Metal; Miscanthus; Molinia eg Sky Racer, and many more. A good site to checkout is bluestem nursery; it has loads of information on varieties and planting information/ care. Have fun establishing your grasses!

Cutting them back annually is not to limit spread - most are clumpers anyway and enlarge or expand their clumps very slowly. But since most die back to the ground annually, leaving dried, straw-like stems and old seedheads, if left in place without an annual pruning or clean up, they become very messy looking and the old dead growth detracts from the new growth.

Calamagrostis and Panicums are good tall growing OG's for colder climates. Most Miscanthus are not hardy below zone 5 and some not even that cold tolerant.