Where should I go for a week or two in Scotland?

I've been to Scotland several times already but would like to go back. I've already been to Edinburgh, Glasgow, Inverness, Skye, Ullapool, Fort William, Stirling, and several places in between by car and staying at B&Bs along the way. What I want for this next trip is somewhere where I can stay for a week or two in a cottage or B&B and relax, do some walking and see the local sights. I would like to be in the Highlands or on one of the islands but am having trouble coming up with a location so I'm appealing to any locals out there for recommendations. I'm planning this trip for next fall, in case that helps, and I'll more than likely be on my own. Thank you in advance for your help!