My sincerely hopes for a speedy, easy, full recovery on the eye surgery. We went to Scotland in mid-August 2013. While the Tattoo and Festival Fringe in Edinburgh were part of the agenda, and there were big crowds along the Royal Mile during the day, things were much less hectic and crowded in the evening. Because the Festivals were in town, some other venues even had special events and performances that weren’t officially part of a Festival - so there are things to see and do in August that don’t have a massive crowd, on a side street a few blocks off the Royal Mile, but that you couldn’t see another time of year. A special performance by piper Ben Miller, who normally performs concerts for thousands, but there were maybe 30 of us in the room at the Royal Oak, is an example.
We then headed to Shetland, and Orkney (Neolithic sights!), which never have massive crowds. Then on to Skye, another place that you won’t quite have all to yourselves in August, but “massive” will only apply to the scenery, the spacious views, and the serenity you’ll experience. Stay on the west side of Skye. Have dinner at the Three Chimneys restaurant. Fort William and Glasgow are also Scottish considerations.
You’ll likely get at least a couple torrential rainstorms that time of year - cozy up in a pub, and you’ll have a few people there, but not a massive crowd.