Oban to Fort William is not much over an hour, I’d be tempted to stop for a cup of tea in Ft. Will, then go on to stay at Mallaig, for an earlier ferry to Skye.
Macaigs Tower in Oban is worth a visit, free, great views over to Mull, and down onto the town.
The Hotel that looks over the bay in Kyle of Lochalsh is a great spot for a drink, we saw seals swimming from there, whales and dolphins have been spotted there before.
Dunkeld and Birnam, there is a lovely walk along the Tay, which takes in Birnam Wood, and the , supposedly, Oak from Shakespeares play. I dont think it is old enough, but it is a big tree. I generally walk trough Birnam town, stop off at the post office for a tea, then walk through the caravan site to the riverside path back to Dunkeld. Then cross the bridge to look around the cathedral grounds. Get back in the car for 5 minutes to go slightly north to the Hermitage, a short walk up to the waterfall, and past the largest tress in the UK.
Pitlochry, as stated above, worth a visit, though its a bit tartan tourist town. There is a lovely walk over the dam, and round the river back to town across the wobbly bridge, but, the dam access, and salmon viewing point, were closed last August when we went.
If you want a relatively easy mountain walk, then Ben Vrackie is one of the easiest Munros to get up/down, not much more than a hill climb. Great views.
Also, Birnam Hill is a pretty easy 2 hour walk with fantastic views, start at Birnam Rail station, and do the clockwise route up, the anticlockwise is quite steep getting up.
I’ve always found Inverness to be a little over rated. I dont think I’d go there to visit again, there isnt a great deal to see. The same with Perth, they are both nice enough towns, but far nicer areas are only 10 miles away.