Geoffrey,
What are the parameters of your trip? Is it a golf trip? Where are you flying in to? Do you only have 5 days on the ground? When will you be going? Are you sure you'll never go back?
I've done the great circle driving tour 5 times now, and you can certainly hit all the far flung places if you put your mind to it and don't mind the (LH) driving. But if you have the option for a few more days or you will go back some day, it just makes so much more sense to limit the driving and focus on a smaller geographic area.
Machrihanish is worth a visit, but if you only have 5 days, it is really out of the way, although I once left Dornoch in late afternoon and got to Machrihanish at midnight, played the next day, and then drove to Glasgow, again arriving near midnight to catch the plane home the next morning.
I wouldn't bother with Kingsbarns unless you're interested in a course that's representative of modern manufactured links. With so many old, natural links courses and limited time, why bother.
If you fly into Glasgow, it's easy to get to Prestwick for a game the day you arrive, and then drive to the next destination.
If you are going in June or July there is a lot of day time hours. It's easy to get in two rounds even at different courses. For instance North Berwick and Gullane or St Andrews Old and New or Crail or even Carnoustie. Around Aberdeen you could go to Cruden Bay and Royal Aberdeen or Murcar in one day. Around Inverness you could do Dornoch and Brora or Nairn.
If it is your only trip to Scotland, then definitely go to Dornoch. It's worth the drive, and as Tom says, it's a beautiful drive. And, you can certainly play there and drive back to Glasgow to overnight before your flight home.
If you can, try to be on the ground for 7 or 8 days, it makes the touring a little more doable.
Once you've been once, it'll be hard to resist the siren call to return again, and again .........