The West coast in general once you're North of the central belt is spectacular. As has been mentioned the A82 can get pretty congested during the summer, still worth it though. It get considerably quieter once you're North of Fort William.
Leave the A82 at Invergarry onto the A87. the A87 from here to the Isle of Skye is unbelievable on a sunny day. Skye itself is amazing but again, gets pretty congested during summer.
The Bealach Na Ba over to Applecross is another great jaunt.
My favourite ride in the country is once you're North of here. The A896 onto the A832, roads are quiet but single track in places, not great for making big miles in quick time but the views are unreal, it's a jaw dropping stretch.