I-81 through PA isn't one of my favorite RV routes. Hills, trucks, and 2 lanes of rough road and never ending construction.
As I recall (been awhile), I-80 across PA is pretty flat for most of it. If you went that way, you limit the distance on I-81 up to I-84 to CT.
One other scenic option is go up to I-90 in Ohio, then pickup I-86 near Erie PA and go across the very southern edge of NY. I-88 from Binghamton is usually fairly light as far traffic and a scenic drive. That would take you back to I-90 into Mass - but a little north of where you want to go... Otherwise in Binghamton, stay with 86 down to I-84 and across. That would take you through the Catskills, which is another scenic drive.
2005 F-150 FX4
2013 Rockwood Roo 23 IKSS