My number 1 tip is to rent a small car. The smallest you can possibly get away with. There are no highways after you leave Edinburgh. The roads are narrow. You are driving on the wrong side. There are raised curbs on the side of the road. Scottish trucks are driving at extremely high rates of speed and are very close to you because the roads are like US backcountry winding roads. You'll want to move over onto the shoulder of the road when a truck is coming at you - but there is no shoulder. If the map tells you it will take 50 minutes to drive from one point to another, expect it to take you 75 minutes or more. And I had a road closed and had to do a 2 hour detour.
Skip Glasgow.
Move those 2 nights to Oban - rent a house - take the short ferry to the Isle of Kerrera and hike to the ruins at the tip of the island, then have lunch at the tea house on a farm near it. It was one of the best experiences I had in Scotland. Afterward walk about Oban and have dinner there.
You only need 2 nights on Mull. It's an hour ferry ride - then you have that day to drive around. The next day do your hike or see the beach. Then leave and drive to Glencoe. Frankly - I don't think you even need to stay there 1 night. I was disappointed in it, but my kids made us do the hike to Haggerts Hut - then we drove to Fort Augustus at the tip of Loch Ness. Nice little town. Great old abbey right on the lake. You could spend 2 nights there and then definitely go to the Isle of Skye. You will need 3 nights on Skye because the drive from Fort Augustus to Skye will take time. On Skye there are at least 3 great things to see / hike and they are spread out. Damn maybe 4 nights on Skye - but you need to book ASAP because lots of english take vacations on the island. Of course, then you need to backtrack to Fort Augustus to continue on to the eastern side of Scotland.
Inverness - meh. Skip it.
Cairngorms - I wasn't able to fit it in.
Pitlochery - nice little town and a good 1 night stopoff before driving to Edinburgh the next day to fly home.