Depending on your interests:
- Corning Glass Museum (requires taking I-88 and I-86 rather than the thruway across New York, which is not enormously different in length and less expensive in tolls)
- Niagara Falls (which isn't on I-88 and I-86)
- Cedar Point (Sandusky, OH) if you like roller coasters
- All sorts of things to see and do in Chicago, but I'm not aware of any great options for camping whilst sightseeing there. The art institute, Field museum, museum of science and industry, ....
Maybe think about taking the northern route (I-94) in one direction; Theodore Roosevelt NP is one stop there that's worth seeing.