I rented a car and like the freedom of going where I wanted when I wanted. But when I got to a town/village where I wanted to stop, I parked in the first car park I came across and walked - it was safer for everyone! I did one commercial tour, at the suggestion of my B&B hosts - Oban to Iona with a pass by Staffa Island via ferry/tour coach (bus)/ferry.

Some of the more interesting places aren't on tour bus routes, and/or you can't be spontaneous. But then I don't do well in large groups either. Follow the leader never was one of my favorite games.

I ordered a tourism book from the Scottish Tourism Board (pre-internet days), and listed out places that sounded interesting, then plotted them on a map, knowing my plane would be landing in Glasgow. After that it was where the whim took me or the suggestion of people I met along the way. I used the tourism offices to help book B&B's if I had trouble getting one on my own. Their fee was nominal, and the service was wonderful.