Dear San,
I know 2 temples in PA, One is Bharathiya temple and another one is an ashram in Philly where you get nice menu of food for free of cost.This inf. is from my frnds who visited there often.
http://http://www.hindumandir.us/east-coast.html#PA
This is the link for temples in PA, where you can find some more temples. If you are planning to visit some other places, there are some like Hershey park - Chocolate factory and amusement park, Crystal cave, Aquarium and some more.If you need some inf. on these places, let me know.I have visited few places, so I can share with you.
On the way to Niagara falls, There's one Glass musuem in Corning, NY which is worth to visit - nice one.This is the piece of inf. i have now.All The Best for ur plan and Trip.
Pinky.