Glad you are doing the Canadian side of the Falls. Do the Maid of the Mist for sure. Corning Museum of Glass is fun and interesting and you can schedule to participate in a glass making activity. If you like outdoors/hiking, check out Letchworth State Park which was voted best NY State Park. Nice hiking trails, huge park, public pool, view of water falls. Another great state park is Stonybrook which has a natural swimming area from damning up the water. It's freezing cold but kids LOVE it. For the Erie Canal you can do a canal boat ride (nice ones leave from Fairport NY and Pittsford NY). You can also bike/walk/run along the Erie Canal easily in the Rochester area.
I'd also recommend Pittsburgh if you are staying on the west side of PA. Depending on your path back West out of NY/PA, I'd recommend a stop in Cleveland for the Rock and Roll Hall of Fame.
Mom to two amazing DDs ('07 & '09) and a fur baby.
Gluten free since Nov '11 after non-celiac gluten sensitive diagnosis. Have had great improvement or total elimination of: migraines, bloating/distention, heartburn, cystic acne, canker sores, bleeding gums, eczema on elbows, dry skin and scalp, muscle cramps, PMS, hair loss, heart palpitations, fatigue. I'm amazed.