In reply to Dave Todd:
Have you been to Mull, and in particular the Ross of Mull?
Shell sand beaches and beautiful pink granite, and the most incredible variety of wildlife (you're practically guaranteed to see seals, and eagles/sea eagles are a strong possibility too). This applies to Mull in general. From the Ross can fairly easily make your way over to Ardmeanach and Loch na Keal, both of which have very dramatic volcanic scenery - think Trotternish. There are endless possibilities for coastal walks.
If you're after history, Iona is a 10-minute ferry ride from Fionnphort. Duart Castle is 45 minutes away by car.
As a base for all this, there's a very nice camp site on the machair at Fidden Farm.
If you're looking for a cottage on the Ross of Mull, this one at Bunessan is fantastic:
http://www.holidaycottagemull.co.uk/