Aviemore- nice walks around Loch Morlich, Pityoulish or Loch Garten- there’s an osprey nesting site near Loch Garten which you may or may not be interested in (no idea if it’s a good time of year for going there).
You probably won’t need a huge amount of time to check out Inverness. The only place I usually pop into is Leakey’s bookshop on Church Street (converted church selling second hand books which is a nice place to pop into for an obligatory bowl of soup).
Towards Skye the village of Plockton’s nice (on the mainland north of the bridge) and am a bit fan of the mountains around Torridon (but am a hiking twat, so I would).
For Skye itself, the Fairy Pools are stunning, but it’s a hike to get there. Loads of places for good views (Old Man of Storr, Quiraing to the north, but again quite a trek, Loch Coruisk and surrounding Cullins further south) but not sure how much you’ll want to tackle in a day.
The A82 on one leg of the journey is a good call, although the road can be agonisingly slow at times. Is worth it for the drive through Glencoe as has already been mentioned. Possibly is better coming at it from Glasgow for views when driving, but if you’re not in a rush and taking time to look around, the direction of travel won’t matter that much.