In that time frame and with young kids I would suggest maybe Oban then up to Glen Coe and Fort William area then on to Arisaig. You’ll see some of the best of the Highland landscapes and the beautiful west coast without using up too much time driving around.
Oban has lots that you can do with kids. Trips out on a boat to see the seals or a ferry to Mull.
Glen Coe – an adventure up into the Lost valley. Scrambling over rocks and up a river gorge at a level that is brilliant fun for kids.
Glen Nevis – Nevis gorge, Steall meadow and himalayan rope bridge. Another fantastic amount of mountain adventure in a short distance and without much effort. Kids would need long arma to get across the wire bridge but they’ll laugh at you wobbling your way over it.
Arisaig for some of the best beaches on the planet. Rocks to scramble on, incredible sunsets over the islands and the kids will make friends if you stay on one of the great campsites up this stretch of coast.
[video]http://www.youtube.com/watch?v=Mihbl48kMcs[/video]