If I had to pick 2, it'd be a 9 ft 5 wt and a 7.5 ft 5 wt.
Valley is a tweener, not nearly as tight as most brookie streams, but not big open water either. An 8 or 8.5 footer is perfect for there. But neither the 7.5 ft nor the 9 footer will have you completely out of place.
Recommend 2 new rods, and you'll have 90% of your bases covered, rather than getting 1 tweener that isn't perfect for anything. If you want to add the tweener later, that's your choice. Getting them both in a 5 wt, remember, allows you to get away with only 1 reel/line combo. Just switch which rod it's on and change out the leader.