Jason,
I don't remember how far apart Aberdeen and Cruden Bay are, but Royal Aberdeen and Murcar are right next to each other and might make a better combo.
If I had to choose between RA/Murcar and Cruden Bay, it is not even close. Cruden Bay in a landslide. The best view while you eat lunch is at Cruden Bay.
Good call regarding Dornoch, it was my favorite course in Scotland on my trip over. North Berwick is great for the golfing soul, if you like quirk. Every hole there is not great, but there are so many funky/cool holes that I would plan on spending the day there if that is an option.
BTW, David Tepper has a place about a par 4 away from Dornoch that he rents out.
Have a great trip.
One other thing, just in case you didn't know about it. Since you are spending 4 days in St Andrews, they have a ticket you can buy for unlimited play on all the courses other than TOC, that I remember seeming like a bargain when I heard about it.