My family is going to be in Scotland for two weeks, but half of us arrive four days early. For those first four days we will start in Inverness. I am stuck between three options: staying in Inverness, staying loch-side near Fort Augustus, and staying in a lodge in Kingussie to be in the Cairngorms. We are definitely leaning towards fishing, hiking, and other outdoors activities for those first four days BUT I also want to spend a day exploring NC500 (which has us leaning towards Inverness for lodging.) I know logistically this is ambitious but we will have a car and don't mind driving.
After the rest of the family arrives we are doing a few days in Dunan to do Isle of Skye stuff, two nights in Glasgow, and then about five nights in Edinburgh.
If you are an experienced hiker then head over to Torridon or Beinn Eighe. Some of the best hiking in the UK! Far better than Cairngorms.
Some lovely scenery heading from that way towards the north coast too. I think it may be part of the NC500 route, but I never specifically follow that when I go to Scotland. I go where is most scenic.
That said, your ideas aren't bad ones either. It's hard to go wrong in the highlands.