We do an annual trip to the Highlands and can recommend the following:
General Wade's Military road from Fort Augustus towards Inverness
The Applecross Peninsular Drive
The Road to the Isles taking in the seafront from Arisaig to Mallaig
The Isle of Mull and Tobermoray
Any of the Speyside Distilleries and Elgin Motor Museum
Day boat trip from Oban to Mull to Iona and Staffa
Jacobite Express steam hauled train from Fort William to Malling and return
The Hill House in Hellensborough (Charles Rennie MacKintosh)
If going to John O' Groats do a such at Castle of Mey
The Gear Glen and Caledonian canal (the lock flights at Fort William and Fort Augustus
There is so much to see that even with your length of stay you will have to prioritise
