I only an hour or so from there, and have driven Rt3 many times. While it would be somewhat slower going than US11, it's not a bad drive, even for a big rig such as yours. I would describe that stretch of Rt3 as "hilly" more than mountainous, and curvy, but not twisty -- if you know what I mean.
US11 is OK too, just not as scenic IMHO. Rt 11B is just as direct, but on higher ground with some great long views north to the St. Lawrence River valley. Or, as the other poster said above, you could go all the way north and take Rt 37 right along the river. No matter which way you go, you'll wind up at Rouses Point to cross into Vermont.
