Thomas
Not sure of the travel times exactly but Boat of Garten to Brora is likely to be a couple of hours ? Likewise Silloth to Southerness, even with the new bypass round Carlisle, that's a couple of hours. Better combo's in that they don't involve as much travel would be;
Silloth & Carlisle or Seascale
Southerness & Powfoot
Boat of Garten & Granton-on-Spey/Kingussie/Spey Valley (any of the 3) with the nine holer at Nethy Bridge thrown in.
Niall
Niall,
That's cheating!!!
Carlisle, Powfoot, Granton, Kingussie, Spey Valley and Nethy Bridge arn't on the list. Perhaps they should be though. I don't dispute the timings but you drive not far from BoG going to/from Brora Golspie when using the A9 hence the linkage and I've done Silloth-Southerness although it's a bit of a pain.
Now if cheating is gonna be allowed, then just a couple of expanded examples could be -
Brora-Golspie-Portmahomack-Bonar Bridge-Tain-Fortrose (plus maybe Invergordon, Alness etc)
or
Pennard-Clyne-Machynys(?)-Ashburnham-Carmarthen-Tenby
ATB