I would recommend going up the west side of the Hudson from Schuylerville on River Rd.
You have to climb out of the river valley to the Saratoga Battle Monument, but I think it is well worth it. River Road has been part of the Mohawk-Hudson Bicycle Club century ride for years and there would be much less traffic than Route 4. Saratoga County has an excellent county and local road system, so anything would be an improvement over Route 4. There is also a 12mile bike path from approx Route 149 in Glens Falls to Lake George Village. I am not a big fan of bike paths, but it wins hands down over that stretch of Route 9. Lake George Village is a resort area and the stretch of Route 9 between Glens Falls and Lake George Village is very busy and commercial during the summer.