Staying in Edinburgh, looking for recommendations

there are plenty of videos discussing your question on youtube.

Definitely do Edinburgh Castle. I liked the Palace of Holyroodhouse, too, on the other end of the Royal Mile, though more of an 1800s fancy house than a military fortress. The Scottish Whisky Experience was kind of fun, but it's definitely a tourist attraction (it's part Disney ride, part whiskey tasting). I would also recommend the National Museum of Scotland, and, if you can, take a day tour of the Highlands. I did the "West Highland Lochs, Mountains, and Castles Tour" with Timberbush Tours (their office is located right across from the Scottish Whisky Experience right outside Edinburgh castle). I loved it, but if you're prone to carsickness, definitely take some Dramamine. My friend was down for the count because how queasy she got from all the twists and turns ofthe drive.