Good advice. OP - You’re probably biting off a little more than you can chew trying to fish all three of those in one weekend. Spring is maybe a little easier to figure out (less diversity of bugs there) but Penns and the Little J can be tough nuts to crack and you’ll probably find you need to put some time into them to figure them out. Sure, can you get lucky and hit a major hatch that’s obvious and easy to figure out and match, yeah, but that’s the exception, not the rule. And it’s less likely that’ll happen in the Fall, versus the Spring during the major hatch seasons. I’ve been skunked plenty on both of them and it took me probably a half dozen trips on each til I at least knew what to expect, sort of. Still doesn’t mean they’ll fish easy.
I wouldn’t expect this little bit of rain to do much to stream levels. Of those three, Penns is in the best shape flow wise by a pretty good margin over the other two. Still lower than ideal, but it currently has the best flow of those three.
As far as what flies, for dries I’d have some Caddis in varying sizes and some Slate Drakes (a generic Adams, size 10-12 ish works fine for this), and some small BWO’s. Your standard generic nymphs will be fine and I’d probably mainly plan on nymphing, unless you get lucky. Unless we get a TON more rain, I don’t think streamers will be very effective.
If it were me, with the current flows, I’d spend both days on Penns and get to know it.
Edit: As you can probably tell already, you’re gonna get a lot of opinions here. The one common theme will probably be to pick one, or two at most, and focus on those. For a quickie weekend trip, on water that’s new to you, it’s easy to burn all your time in the car driving around. Don’t do that. Park, and fish.