Oban lies approximately 100 miles west of *Perth, and can be reached quite comfortably within 3 hours driving time [from *HERE] amidst beautiful ... ever-changing scenery. In fact I bought my first wife's engagement ring there.
Caledonian MacBrayne operates a regular passenger/car-ferry service to the Western Isles ... including the Island of Mull (of which the small town/large village, Tobermory is the capital) throughout the summer season ... although the service tends to be curtailed somewhat from late October through to February/March (depending on the weather and tidal conditions) at that time of year.
If you should decide to avail yourselves of the one-hour sail to Mull (once the boys are a little older) it would be well worth your while leaving the car at Craignure (the ship's first port of call) and undertaking the 30-mile coach journey to the hamlet of Fionaphort, where there's a much smaller ferry terminal linking with the tiny island of Iona ... historically the site where the Irish monk, St Columba, landed in the year AD 563 (or thereabouts) and introduced Christianity to Scotland. There is a restored Abbey here, with an adjoining burial ground where former Labour leader, John Smith is interred - alongside ancient Scottish Kings & Queens.
Thanks, Ann, for initiating this excellent thread.