It takes place at the end of May, 25/26, so that kind of determines your timetable. All the info is on the website and they have a caravan park so it may be an idea to book a pitch as I imagine it'll be pretty busy - no motorways up there.
Edinburgh is certainly worth a visit, but it's one of the most congested cities in the UK. Again, a campsite might be best. The C&MH Club have one convenient nearby, or stay at the site in Melrose, itself worth a visit and get the train from Tweedbank.
There are a few wilding sites in Glencoe or just before, but again it's a busy place in high season, but probably ok in May early June. Then Fort William, a bit of an eyesore, but trying to improve and of course some top class mountain biking country and the highest UK mountain - worth a look or even a climb up.
You could get the wee Corran Ferry onto Ardnamurchan and the most westerly point on the British mainland, with the option of a small passenger ferry to Mull and a look at the painted houses of Tobermory. (lots of fun on some single track roads - let people overtake, it may be a doctor or home visitor)
From Ft Bill take the road to Loch Cluanie and Kyle of Lochalsh and be amazed at the run down to Shiel Bridge. Then Eilean Donan Castle (we lived nearby for a few years) - it's a horrible pastiche rebuilt by people who knew nothing of historical accuracy but everyone goes there and it is "iconic".
You could try the Glenelg Ferry to Skye (back to Shiel Bridge from Eilean Donan), the last turntable ferry in Scotland. You go over quite a high pass to get there, so you may prefer to go on to Kyle and the Bridge.
Possibly the most "must-see" beach is Sandwood Bay. There's a camper stop at Kinlochbervie (https://klbcompany.wordpress.com/loch-clash-stopover/
) and then a walk to the bay: https://www.walkhighlands.co.uk/suth...wood-bay.shtml
Just a few of the many.