Where are you looking at staying? Motel or camping? Do you have PA license, NY license or both?
East is entirely in NY as is the Beaverkill, Willowemoc and Neversink. These waters require a NY license. The lower East can be VERY hot and cold. It tends to be awesome or awful. If you like spring creek / chalk stream type of fishing, try the upper East. It's about 13 miles of glassy flat water with fairly easy wading. You might spend 45 minutes stalking a fish just to get one cast. The fish appear to be 10"-12" but they aren't. I've taken fish over 24" on dries in that river....they're there but tough to get close to.
Beaverkill, Willowemoc and Neversink.....don't overlook them for producing crazy hatches, lots of fish and some large fish (20"-24"). Typically easier to fish too.
West is in NY for the first 6-7 miles and then it borders both NY & PA until it meets the East and forms the Main. NY license needed for upper section and special regulation area. PA license is good from monument pool to the junction pool.
PA license gives you rights to either bank of the Main. At that time of year, fishable section from Hancock to Narrowsburg (30+ miles).
It's likely that you will run into bug soup at that time of year so have every pattern known and be prepared to change flies often. If you haven't fished it before, a majority of the fish are done with a sloppy cast so get into position prior to casting. 5-6 weight rod is standard. Be ready for wind, wind and more wind. If the flows and weather continue to be like the early part of the season, you could have higher than normal flows. Wading may or may not be an option.
If you haven't been there before, it's a lot to take in. You can be on a pool that has 5 different blanket hatches. You've had 200 fish rising for 8 hours straight. Your brother is less than a mile away and he's seen 3 bugs and 1 rise. 🙂
Best possible thing you can do is get Paul Weamer's book and digest it quickly. It discusses flows, launches, hatches and give some tips on how to approach fishing the rivers.
** There is a ton of posted property along all of the rivers. Please respect the landowners rights. Some might yell, some might shoot in the air and others might offer to pound your head flat (I had that very offer one day). In NY (East specifically), the landowner owns the stream bottom. Wading or even dropping anchor is considered trespassing. I can think of 4 landowners in particular that will video and contact state troopers if your foot or anchor touches their property. That would apply to the upper and lower East. Keep your feet wet on the West and Main just to avoid any land rights dispute.
