I'm not familiar with 7b night temps (used
this link as a reference), but if you can provide night temps between 41 and 50 F during fall, I would suggest Den. nobile (yamamoto type). They grow like weed and are hard to kill (for me).
I bought a young plant with 3 canes that grows 4 new canes this spring and they grow fast!
Dendrobium kingianum is very hard to kill too :-) and needs the same night temperatures during fall to bloom. Besides the flowers from kingianum smell like honey!
You also might considder plant from the oncidium alliance if you like them. They like intermediate temperatures.
Nicole