The Far North
There are some good things to see in the far north too, but I must second Tom Gaynor's recommendations that Dunnottar is stunning and the Ballater, Corgarff, Grantown-on-Spey road (A939) is great fun.
The castles like Castle Fraser, Drum Castle, Crathes and Craigievar are all very interesting but unless you have loads of time it might be better to pick one of them, and then go to Dunnottar.
The A9 north of Inverness follows the coast, and goes through the small towns like the southern part of the A9 used to. It is very scenic, and there are some twisty and hilly bits around Helmsdale and Berriedale. The road has been straightened out over the years but the Berriedale Braes might still be a test for the brakes. It would have been a formidable road in the early days. There is a long single track road (A897) which goes inland at Helmsdale and goes north through some really wild places but to get to John O'Groats I'd go to Wick and up the east side. Don't bother with the A9 which goes off at Latheron to Thurso unless you have got a ferry to catch, it is all peat bogs and windmills. The coastal road in much nicer.
The road along the top (A836), Thurso, Bettyhill, Tongue is also very scenic. Keep going around Loch Eriboll (beautiful), and to Durness and onward. I have been to Lochinver by the main road (A837) but not the B869 which looks very interesting - lots of arrows on the map. Just south of the B869 turnoff you go over a modern bridge, at Kylesku, where once you would have waited for the short, free, ferry trip.
Near Wick there is a castle ruin, Girnigoe and Sinclairs, which I first climbed about on in 1971. A few years ago part of it had been gated off so you couldn't crawl about in the dungeon or get too close to the sheer drops to the sea, but it is still good.
If you have got that far north, and don't mind a ferry trip, why not come to Orkney - good fast roads, no traffic, bit of cow muck and the occasional escaped sheep on the road. The Pentland Firth has a reputation for being rough, but I have had many more calm crossings than rough ones, and the rough ones have all been in the winter.
There aren't any midges on Orkney (maybe it is too breezy for them), apart from on the island of Hoy, where there can be a few!
Pete
Wednesday 13th in the afternoon I think.