Considering the remoteness of much of the country, there is a surprisingly good network of public transport which can get you around, especially in the most visited areas. Its definitely worth considering if you want to see a lot and free yourself from watching the road !
Did you know that from 1 June to the end of August the John O' Groats Ferry runs a twice daily service from Inverness to Kirkwall, travelling by coach up the lovely coast of Caithness with a 40 minute ferry (weather permitting) ? What's even better about this is that it costs only £25 one way, and if you hold a Scottish seniors bus pass you only pay for the ferry ! What a great way to get to know the country better, and completely stress-free ;-))