So much to do in Buffalo. History buffs can use the Boy Scout Historical Trail program to visit some extremely vital history spots in WNY. http://www.wnyscouting.org/resources/the-niagara-frontier-trail-medal-program/67514
For instance, the Teddy Roosevelt Inaugural site on Delaware, the Niagara Falls underground railroad museum next to the Falls train station, Fort Niagara, (as has been mentioned billions of times) the Martin house, Forest Lawn Cemetery, the Power Vista (for the engineer minded), Canalside and the naval museum.
That's only the tip of things to do outside of stuffing your face with food and drinks.
Best of all, enjoy your trip!