I realize this is a Welsh forum, not a Scottish one, but I think we have a number of (active) members in Scotland, so I’m hoping… We are considering a trip to Scotland next spring and, having never been there, are looking for suggestions for places to go, do, see, that we shouldn’t miss.
Diolch!
Stirling: Castle, Bannockburn battlefield, Wallace monument, nice little town right on the edge of the highlands, too. A bit clichéd I suppose, but one of those places you’ll regret not going to.
That’s a thing called the Northern 500 - it’s a drive from Inverness around the highlands past the lochs back to Inverness. I want to do it so badly!
Glen Coe (in Argyll) and Glen Brittle (on Skye) have got to be towards the top of the list.
Orkney
There’s too much stuff. It’s BIG. Set aside a year and you’ll still have things you haven’t ticked off.
But Skye is my favourite spot so far. I could easily spend a couple of months just there… 
Needless to say Edinburgh. We drove from there to Oban via the highlands and the lochs, lovely trip.
I have been suffering from the “Cannot choose what to recommend” syndrome. Then I saw Orkney and that was the one place my friend and I determined to visit while we were fit enough and I am truly, truly glad I went. They have found a lot more since.
https://www.nessofbrodgar.co.uk/about/the-ness-on-tv/
is a link to three programmes about the on-going excavations on the Ness of Brodgar of what could easily be the cradle of British culture, language, and civilisation, pre-dating Stonehenge by a lot!
We were very glad we braved the fairly lively passage and took a car over, as it helps to get to everything we wanted to see. If you are totally uninterested in the past, it is not the place you would choose! But then, I don’t think anyone totally uninterested in the past would choose Scotland!
NB since the Skye bridge was built, it has become very crowded in summer!
Assuming you don’t have the year Aran wisely suggested, six months might be just enough time to see the island of Mull. Wonderful walks and beaches, amazing boat trips to Iona and Staffa, gem of a tiny theatre… Top tip - head down otter-y lochs to base yourselves in a fisherman’s cottage at Lochbuie, and watch sea eagles raise their young. By autumn, rutting red stags will have come down off the mountains to roar outside your window. I am only sharing this private heaven because I love SSiW so much.
Hmmmm, that sounds like a plan… hmmmmm…
To be fair, as with the US (I guess), you don’t need to visit everywhere in one visit. I’d go for a touring route to get to a chosen centre to stay at for at least a few days.
I’ve heard of people trying to visit everywhere in the US in one visit, but it is absolutely impossible to do as a visitor. One reason we like traveling in Britain - the distances aren’t as far. We joke about “imperial miles” because it seems like it takes much longer to drive, say, 20 miles in Britain than it does in the US, but I think that’s just because we’re new to the places we are driving!
Thank you to everyone who has posted suggestions so far, and please, keep adding them if you think of something else (or want to expand on someone else’s suggestion).