Hi again, Christina,
I can't believe someone remembers my old posts! Let alone refers back to them! As you and your husband don't enjoy hiking, that leaves out a few places which I would have recommended for hikes. However, the cliff walk at Arbroath is an exception. It's a beautiful walk on a paved path, high above the cliffs which tumble down to the North Sea. Although it's possible to walk all the way to the end, and catch the bus back to Arbroath from Auchmithie, the most sensible thing to do would be to turn back when you feel that you have walked enough.
As far as walking through towns, Aboyne is a bit too spread out, and doesn't really have a "downtown" area. Both Ballater and Banchory do, however. And both have plenty of places to stop for a meal or drink (or both!). While you're in Banchory, don't miss the Falls of Feugh, which I've probably mentioned in several posts.
As far as your lodging goes for the Braemar Gathering, how far outside of Pitlochry are you staying? Did you consider Blairgowrie, or possibly the Kirkmichael Hotel in Kirkmichael? I was hoping that the Boat Inn in Aboyne would be available, but it appears to be fully booked for that weekend. It looks as though the Burnett Arms in Banchory still has rooms available at a reasonable cost, but if you're interested, check out the reviews before making your decision.
If you do decide to try the fly cemeteries (and the stovies!) at the Upperkrust, you can park at the Morrison's supermarket on West North Street, walk up Littlejohn Street, cross over Broad Street, and walk down Upperkirkgate to the restaurant. Be sure to get back to Morrison's within the two hour time limit! You'll get to see the outside of Marischal College on Broad Street, which is the second largest granite building in the world.
I hope that all of this information helps you with your decision making!
Best wishes,
Mike (Auchterless)