There are so many beautiful places along the west coast its hard to know where to start! A favourite of mine is to travel up the west side of Glasgow , round the west side of Loch Lomond and down to the Mull of Kintyre. If you stop off at Tayinloan, you can take the ferry (20 minute crossing) to the island of Gigha.
The only trouble with this route is that once you get down to Campbelton and have stopped there the only road north again is the same one you travelled south on (A83).