Totally agree with this. Near Tongue, there is a road up to Talmine, which is nice, Portvasgo maybe not. Also, on the road around the loch, there are signs pointing out the local wildlife, the various mountains and the spot where John Lennon crashed his car.
Also, you are right, the Caithness by-pass is nicer heading from Melvich to Helmsdale although the other direction is okay as well.