We were in Scotland for 2 weeks earlier this month and loved it. We were in Edinburgh for a week, so had an apartment at the southern end of the Royal Mile (the street that goes by different names as it goes along) that runs between the Edinburgh Castle and Holyrood Palace, where the queen stays when she's in town (but am not familiar with the Victorian townhouse). Both of those places are among the top sights. Walking in Edinburgh (plan on some uphills and downhills) affords lots of intriguing architecture. The 12-year old Scottish Parliament building, just across the street from Holyrood, is modern and might be of great interest to your son. We also enjoyed our visit to the former royal yacht Britannia, which is moored in the harbor outside of a big shopping mall in Leith, a town to the north, accessible by a short bus ride (we took Bus #35, but others go there, too). If you have really limited time, the trip out to Leith and back might not work for you, but otherwise you can see a grand, floating palace. The city's full of museumes, too, mostly free. Rick Steves' Great Britain (and also the separate Scotland-only) guidebooks list top sights, in order of significance (although you may have different priorities) to help make the most of your time.
We drove on Skye (challenging driving on the left, on narrow roads), so if someone else is driving on your tour, you can enjoy the sights and not have to watch the oncoming traffic! Coming back to Edinburgh, we passed the Kelpies on the highway, but didn't have time to stop. They're much nicer than the sinister blue horse sculpture outside of Denver International Airport! Here's a link for info: http://www.thehelix.co.uk/plan-your-visit/getting-here/
Near the Kelpies is the Falkirk Wheel, an engineering marvel. We didn't get time to see it, but again, it might be worth investigating, if you can fit it in and can find a way to get there -- a little ways west of Edinburgh.