So, not sure if you were looking at one of the tours that go up to Loch Lomond, but there's also a lot of history that's part of the journey, and so it's not only the Loch itself, which is beautiful from many prospects. To be honest, this is some of the most beautiful, and incomparable landscape I've ever seen, and this includes South Island of New Zealand, which is utterly spectacular. But after seeing Scotland on this journey along Loch Lomond, I know when I see it in a film or movie, before it's ever even identified that this is Scotland. It's gorgeous and has uniquely stunning qualities.
Along the way there were stops to get out and check out pastures with wildlife, and even they look different than what I'd ever seen (though a life long city resident, admittedly I'm no wildlife or farm animal expert) but the highland flora and fauna are truly distinctive and lovely. I had a moment with a highland cow... we locked eyes, she or he slowly started to walk towards me, it was just one of those things, and again, me and large beasts? Not really a thing, but this was awesome.
What's also cool is the weather sort of changes as you go, you're up and down hills, winding around death defying single lane roads gripped to the hill, but with these vistas that go on and on, the Loch is there, and there, and there.
As for the history, well you're going along the way of Rob Roy, learning words of Robbie Burns, old Scottish songs, and of course, William Wallace. We visited Stirling Castle, and from there, in the distance, you can see a memorial for William Wallace, though it was meant to be discreet and out of the way so as not to draw too much attention or destruction from certain neighbors to the south.
I had more time to choose what to do, so I can understand that it would be difficult to decide. There are amazing places in Edinburgh, it is full of history, and even the "newer" part of the city is great to explore. It *might* be enough to spend time on the Royal Mile in Edinburgh, and then from there, you can catch a Rabbie's tour to Loch Lomond. I don't know that you'd have time to go into the castle, but to be on the Mile would provide a wonderful experience of the old city, but you'd be up in front of the castle, you could see St. Giles Cathedral, and whisky places and historic architecture, tartan and wool shops, and more.
If it would be your only visit to Scotland ever, I would be sorry for you to miss an opportunity to experience a bit of the unparalleled country and the glorious city. If your schedule permits, perhaps this would be a way to make it work. I have been to Lugano and it is beautiful (I know Como is a thing unto itself) and there are many beautiful lakes and rivers throughout Europe, but the panorama is simply breathtaking, which I think is often what does it, I'm sure this is part of it in Como, albeit in different ways.
Something to think about? It might be a jam packed day, but it would be truly worth it. Good luck 🙂