First, let me say that Scotland was roughly ten times groovier than I thought it was going to be. My wife and I had been to England and Ireland many times, only once years ago taking the train from London to Edinburg and back for a pin-in-the-map day trip that I can't recommend.
Our recent trip to eastern Scotland began with a flight from Philadelphia to Dublin, where we hopped on a little prop plane for Edinburgh. Dublin has the advantage of a special deal with US customs and the UK. Look into it. Once in the UK, we never rent a car, and we have only taken a taxi once. It's all trains and buses and feet, which are better than a car because you don't have to drive them or park them. We walked around Edinburgh, did the castle, high tea at Holyrood, etc. Then we went up to Inverness for a night (have the Cullen skink at Hootananny) and took a bus all along Loch Ness to Fort Augustus with its bijou Clansman Center, a terrific little museum all about, well, you guessed it. Back up the Loch to Urquhart Castle, hiked to Drumnadrochit, bus back to town. Train back to Edinburgh.
My wife and I found out long ago that jet lag hits some people harder than others. With us, third day on the ground, I turn into Homer Simpson, and she turns into Satan. So, we instituted "ditch day". We each pick a different place and do a day trip alone that third day. It has been a huge success. This time, I went to the Borders for the Mining Museum, where they actually take you underground and all. had lunch at the Dean Tavern, one of only four remaining Gothenburg pubs, and strolled along the Tweed to Scott's Abbotsford. Boy, I'm making that sound almost as much fun as it was. She went to Perth and Dundee.
We bounced around some. I'm not going to try to remember the exact sequence of events, but Stirling and Castle, up Abbey Craig to the Wallace Monument, the Falkirk Wheel, Linlithgow Palace, and finally sunset at the astonishingly magical Kelpies.
I have restrained my urge to comment on these places as I mentioned them because I could run to maximum length raving about each and every one. I can't wait to do western Scotland and the deep Highlands, not to mention Skara Brae and the Orkneys and ... somebody stop me. I'll leave you with one bit of advice: have a single-malt.