Zone 7 offers a huge selection of grasses.

My suggestion is to look at the grasses that are already native to your area and begin there. I'm on the gulf coast and use similar grasses as your area, although I'm able to plant some of the tender perennial grasses and get away with it.

Here is a list of AL native grasses:

Grasses/Grass-like plants
Agrostis scabra (ticklegrass, fly-away grass)
Andropogon gerardii (big bluestem)
Andropogon glomeratus (bushy bluestem)
Andropogon ternarius (splitbeard bluestem)
Andropogon virginicus (broom sedge)
Arundinaria gigantea (giant cane)
Bouteloua curtipendula (sideoats grama)
Carex pensylvanica (Pennsylvania sedge)
Carex plantaginea (plantain-leaved sedge)
Carex stipata (awl-fruited sedge)
Chasmanthium latifolium (inland sea oats, wild oats, river oats, broad-leaf uniola)
Danthonia spicata (poverty grass)
Distichlis spicata (seashore saltgrass)
Elymus hystrix var. hystrix (bottlebrush grass)
Eragrostis spectabilis (purple lovegrass, tumblegrass)
Juncus effusus var. solutus (soft rush)
Leersia oryzoides (rice cut grass)
Muhlenbergia capillaris (gulf muhly, hair grass)
Panicum virgatum (switchgrass)
Saccharum giganteum (sugarcane plume grass)
Schizachyrium scoparium (little bluestem)
Scirpus atrovirens (dark green bulrush)
Scirpus cyperinus (wool grass)
Scirpus tabernaemontani (great bulrush)
Sorghastrum nutans (Indian grass)
Spartina patens (marsh hay cordgrass, salt meadow cordgrass)
Tripsacum dactyloides (eastern gamma grass)
Typha latifolia (cattail)