In my experience, Rangeley is the best easily accessible location in Maine to see Canada Jays. Not sure if you're thinking about winter or summer birding but for winter birding, I don't know if the Boy Scout Rd is plowed or not. Routes 4 and 16 are generally too high speed for comfortable road-side birding but there's a bunch of paved and dirt plowed roads in the area with some good boreal habitat. One idea is the Redington Rd off Rte 16 just north of Rangeley. There's a utility building about 1/4 mile down this road on the right where I've had Canada Jays. Last winter they were putting out seed there. Another idea is Dallas Hill Rd, the access road to Saddleback, I've seen them about 3 miles in on this road. Here's a
map of eBird sitings (need to zoom in) the last several winters and there's a bunch of other side roads near Rangeley with sitings. Looks like several recent ones near Errol NH.
A fun winter birding loop is Rte 4 (or Rte 17) to Rangeley, then Rte 16 through Errol and Rte 26 over Grafton Notch and back to the Bethel area. There's a good chance of also seeing irruptive species on this route. This year, you may run into Pine Grosbeaks, Evening Grosbeaks, Bohemian Waxwings (check the crabapple trees in towns), Common Redpolls (birches or alders), Red Crossbills (spruce trees), or Pine Siskins. Change the species in the eBird map to any of these, and you can see where recent sitings have been. Boreal Chickadees are possible in any good stands of spruce anywhere in the area but they're more shy and less numerous than Black-capped. Listening for their slow weezy call is the most likely way to find them.
Glenn