I'm not a Buffalo native, but I have been living in the Buffalo/Niagara area for about 2 years now and I love it! I didn't see anyone mention Marineland in Canada, but that is definitely one of my favorite places to go. You can feed and pet beluga whales, go on rides, and see all kinds of animals. It's really a lot of fun. Also, on the American side there is the Niagara Aquarium which I have heard is really nice. Also over there, if you want to do some shopping, are the Niagara Falls Oulets.
For food on the American side, if you have a car, I would go down to elmwood village in Buffalo. Blue Monk on elmwood is one of my favorite restaurants of all time. It's Belgian style and they have tons of interesting beers on tap. Another good restaurant on elmwood is Cole's. Basic American food and tons of cool brews also. If you're looking for something a little nicer or just for fun dessert there's Chocolate Bar on Chippewa street. It's really delish. And Thr Elmwood area is really just nice for hanging out. There's two art galleries I think on Elmwood as well as shopping.
Let me know if you have any questions. I live maybe 15 minutes from the Falls and I think the American side has a lot to offer if you know where to look.
Ps. If you do have a car, there is a drive in movie theater maybe 20 minutes from the mall. It's around 8 bucks per person for a double feature!