My daughter and I have 4 full days in Scotland the 12-15 of August. We will be based in Edinburgh those days. What would be the best use of our time while in Scotland? We would love to see Inverness and the Highlands, as well. My daughter would also like to see Alnwick Castle, as she loves Harry Potter and it was filmed there. IS there possibly a day tour to ALnwick? Also, we could potentially rent a car if that would make things more accessible.
Alnwick is a fair trot away from Edinburgh - if not driving you'd need to get the train from Waverley to Alnmouth then get the bus (or a taxi, if there is one) to Alnwick. With all the changes of transport, with the time delays that involves, and the inflexibility of schedule, if the extra cost is not too much an issue I'd say rent the car. That way you can go across the pentlands and the Northumbrian moors if you have time, or just bomb down the A1 if you start off later. Also, on the way back up and if you have time (and the tide is right) you could stop off at Lindisfarne...
All told though it's a full day out and not something I'd normally recommend bothering with. However if your daughter has that as a personal must-do it'd be a pity to skip it, just to cram in more highlands which would have less personal significance. Ultimately a lot of sightseeing is about scratching the itch - the most boring field can be important enough to be worth visiting, to someone!
I think I can help you. We did a one day tour to Alnwick Castle from Edinburgh last Summer. Look Up Rabbie's Tours online. There is a one day trip to Alnwick that we took. Rabbie's will get you there. You pay for your own admission once there. We had a great time at Alnwick. Wish we had a couple more hours there. Go directly to Alnwick website to look up admission price options. You can get castle only (which we did due to time constraints). You can get garden only. Or, both. You don't need to buy tickets in advance. Pay "at the door" is better so you can get a Rabbie's discount.
4 days is not much time. You may want to focus on Edinburgh and one other place. To do both Alnwick AND the Highlands is pushing it. You may want to do 2-3 days in Edinburgh, then get a Rabbie's day trip to Alnwick or a Rabbie's Tour to the Highlands. Stirling Castle is another great option for a day trip.