Royal Aberdeen is a true beauty, best (and toughest) course i've ever played. Especially the first 9 is spectacular, so don't forget your camera
Make sure you bring jacket and tie to get access to all the rooms in the clubhouse. Otherwise you can have a drink at the bar, but cant enter the lounge.
Cruden Bay is in the same category, also a very nice course.
And as mentioned before, rainggear is necessary, you probably won't play a full round without some rain.
(Unfortunately I haven't played any of the St. Andrews courses yet, because the only time I was there, was during the '10 open)