For Seneca Lake, there is a State park called Walkins Glen at SW of Seneca Lake. It is a gorge with water falls, pretty nice.
For Cayuga, on the west shore is Taughannock State park, another gorge with a water fall. The city of Ithca, where Cornell University is, is located at the southeast corner of the lake. You can visit the campus.
These are not famous attractions, but a nice place to spend a few hours. From Corning, you can take highway 13 (?) to reach Seneca Lake, Cayuga is just 10 milkes east from it.