I say this with great humility as I realize you have much more travel experience than me Rotten Ronnie, but I feel that the only trip listed that qualifies as a comfortable weekend trip is the one to Renovo. The others require 4 days to take in for maximum enjoyment.
My adventure tends to be riding the roads to and from, the people, the culture and the meals along the way. So Lake Placid is a haul and the Catskills are a three day ride plus if you were taking it easy and exploring the area.
Riding solo I have no issues with 1000km days, but prefer 800km, and 500km if the route is twisty such as the Blue Ridge Parkway or if I'm riding on gavel such as the Trans Labrador Highway. These figures include hotel/motel as opposed to camping. I'm not as fast as some here at packing up my gear as I'm not a morning person. I have posted some rather long rides here, haven't I?
I tend to get far too many shots like this...
You've got a great point. For my first trip with pillion I'd try for 500km days and really nice stops enroute that give you that "Ah, beautiful!" moment. Shared vistas, good food and a comfortable room at the end of it.
Maybe St. Catharines and the Niagara Pkwy into Niagara-on-the-Lake and then the falls all the way down to the Fort Erie border crossing, Lunch Stateside, then down to Springville NY where you can launch off into the Park or get a room for the night.
Google routed this via the fastest roads, I'd hop off and take secondary roads. There's some lovely Amish country through the middle New York section.
http://g.co/maps/p33pc