A must see
Edinburgh is a really great place for kids and adults alike. It has a lot of history - take advantage of walking tours, they are a lot of fun. There are castles, shops, parks and even some hiking all within walking distance. I could have easily spent way more than my three days there.
Insider Tip:There are lots of things to do for free - museums are free, Arthur's seat is around the corner. Find a hostel with free walking tours and you are set!