Any interest in an amusement park? If so then check out Darien Lake. That's close to the outlets and the RV park is attached to the amusement park so it's super convenient to go back and forth ... they have added some new rides and water park attractions and if the weather is warm that might be a fun stop ... the RV park itself isn't anything special but it's so nice to be able to go back and forth to the camper during the day ....
Also, not sure which direction you want to go in but there's a KOA Association Island in the 1000 Islands area - no beach swimming there but a pool and great boating and Brennan Beach is closer to Syracuse and that's on the water ...