Usually I try to push people to the Borders or Galloway as well as the Highlands, but if you only have a week that'll be a lot of driving. So I would second the recommendation to head further north from Skye and spend sometime up beyond Ullapool or round the top end of Scotland.

Let me know if you'd like accomodation recommendations or cheat-sheet locations in Coigach. I usually take abstractions, but here's an overview looking north from Achnahaird:

http://web.telia.com/~u46133221/pics/achnahaird03.jpg

Take your wellies.