The Grassmarket is a great location. Easy walking distance to a number of fun pubs, Edinburgh Castle, and the Royal Mile. Friends stayed at the Apex hotel there. They said it was a bit noisy from the street side, but otherwise comfortable and included breakfast. We enjoyed a stay at a 1-bedroom AirBnB flat that had a hideabed in the living room. https://www.airbnb.com/rooms/2462829 Our host, Lynne, was great to work with and the flat was just a couple blocks from a grocery store in one direction and the Grassmarket in another, on a bus line, and we had a view of the castle from the kitchen table. The only drawback was the small shower, but everything in the flat was well-maintained. There are a number of AirBnB units in the area.