You don’t say what your transport will be. But by far the best way to see Scotland is by hiring a car, not hugely expensive September/October, and get yourself a tourist map with all the places of interest high-lighted. Head north, for me it would be up the west coast, and call in at the tourist information offices on the way. Where you can book your accommodation for each day ahead.
If relying on public transport you could be spending a great deal of time studying timetables and waiting for connections. Though, which, if you are in that frame of mind, can be enjoyable and relaxing.
Good luck, I wish it was me.