The standard, for good reason, on said streams is a 9' 5 wt for an all 'round, do it all type thing. That's assuming you're talking about graphite sticks. A 9' boo stick is very heavy indeed.
If you are primarily a nympher, maybe a touch longer. If you intend to maybe take it on smaller streams once in a while but don't want to buy a separate rod dedicated to that, a touch shorter.
If you're mostly gonna throw dries or small nymphs and rarely if ever throw streamers or heavily weighted nymph rigs, then opt for a 4 wt instead. If you want it to double as an ok bass rod and be able to handle a once in a blue moon steelhead trip, opt for a 6 wt instead.
And for what it's worth, if I had a different rod for each of the big 4 in central PA (Spring, BFC, Penns, LJR), I'd have 4 wt for Spring, a 5 wt for BFC, and a 6 wt for Penns and the LJR. But a reasonably powerful 5 wt covers them all just fine.