Islay's also a great place for a cycle trip.
But if your driving there then definitely its definitely worth a side trip to Campbeltown to visit the Springbank distillery. It's pretty much the only place left where you can see the whole whisky-making process on the same site. (You can also do this at Kilchoman on Islay, but that is a very small farm-based distillery)
Springbank make some of the very best malts produced anywhere. They also make a peated version (Longrow) and an Irish-style triple distilled malt (Hazelbank).