Do NOT miss seeing Eilean Donan Castle in the Highlands. It is a tourist-stop but dear lord, so beautifully restored and the guided tour provides amazing insights into the everyday lives of the people who lived there. It's reportedly the most photographed castle in Scotland, and for good reason. See,
Welcome to Eilean Donan Castle | Eilean Donan
I also recommend traveling by Scotrail (you can buy the tickets ahead of time online) and CalMac Ferry and local bus. Get a good map of Scotland and plot your path! We flew into Glasgow, took Scotrail to Ft William, stayed there for a week, took ferries to Skye and the small islands, enjoyed pubs and live music in Mallaig (great little fishing village). . . there's a picturesque little village on the shore of Loch Lomond called, Luss. . . it would be lovely to stay in one of the self-catering cottages there for a few days. (see,
www.scotland.com/blog/luss).
Finally, Stirling Castle is another do-not-miss. . .in fact, the entire city is like walking through a living museum. Got to spend at least a day there!
bon voyage!