Anyone here familiar with Scotland?

The Kelpies are pretty touristy but they're also very impressive and are only a short trip from Edinburgh so I'd say are worth a look. Same goes for the Falkirk wheel. Neither will take up that much of your time.

Glasgow. Edinburgh is lovely but Glasgow is a very different city and definitely worth a trip. Some great museums and places to visit, I like the Botanic Gardens and the Kelvingrove Museum but there's plenty for everyone. I suspect taking the train is the easiest way to do that journey.

If you want a multi-day trip out I cannot recommend the Ardnamurchan peninsula enough. Fort William, the "city" (lol, population 10k) in the area is nothing special but the area it's in is some of the most beautiful the entire UK has to offer. Corrachadh Mòr is 100% worth driving several hours to see, and the best bit about coming from the central cities is you get to drive north up the A82. That route is easily one of the top five drives in the country, as you go up past Loch Lomond make sure you stop for some fish-based lunch or snacks. When you hit Bridge of Orchy and get up onto Rannoch Moor and over to Glencoe it's just glorious. Long, winding curves on a really nice road through some o the finest scenery you'll ever see. Even in the rain it's a beautiful trip, I've done it in rain and sun and fog and once, very memorably, at sundown on a cloudless night as the stars came out.

The only problem is that it's probably not a viable day trip. If I were you I'd try to find an air bnb or even just a travellodge as far west as you can, which should be fairly feasible as long as it's not currently the school holidays (it is this week in England but Scotland has different times)

I don't really know the east coast though I'm afraid. I once had lunch in Dunbar and it was very pleasant but there wasn't much there apart from lunch. If you like gardens and don't mind a bit of a drive, Alnwick gardens are very nice (it's pronounced "ann-ick") and the famous Barter books are just around the corner there if you like books. The coast road south from Edinburgh is also a very nice drive so could be a nice day out. Might be worth booking tickets for Alnwick in advance if you do decide to visit.

I found Rosslyn Castle beautiful and interesting (if you just avoid the Dan Brown Da Vinci Code-nonsense). (I highly, highly recommend living in Landmark Trust historic buildings next time anyone vacations in the UK!)

Just going for a nature walk to see the natural scenery that's inspired golf courses all over the world was very enjoyable. (It's okay to get wet).

There are several Roman history sites and museums that are a lot of fun. An outing to Hadrian's wall near Newcastle could be an outing.

Also just going for a drive to a village of your fancy is fun. Driving on old country roads to see what the UK is like outside of the large cities is a change of pace for sure.

Mat also has a lot of great suggestions. If you don't like touristy stuff, you can definitely do without seeing Edinburgh Castle, The National Museum of Scotland and The Scottish National Gallery. They're okay, but other cities do the same things much better. The English have hoarded most of the best works in London, as one would expect.

I'm not sure if you'll have the time, but the isles out on the west coast are pretty awesome! I had the chance to explore the Isle of Mull on my bike and it was gorgeous! Also, Fort William and Glencoe are great for hiking and mountain biking if that's something you are into. I really enjoyed Glasgow, it felt like the working city vs the tourist city similar to Oakland and San Francisco. There is the John Muir trail from Dunbar to Edinburgh as well which is beautiful.

The last thing I'd suggest is getting a little book on the local folklore. I love the history of the Kelpies, Brownies, Selkies, and all the other, more specific, creatures!