We loved our recent 3 night stay at Princes Street Suites. The staff we met were lovely, the location is incredible - 2 mins from St James' Quarter which is a mall with great shopping and loads of choice for dining (in or take away).
The property is a 15 min stroll from Edinburgh Castle (with young kids); it's ideally located for the Museum of Scotland, Dynamic Earth, Calton Hill, Arthur's Seat, the Museum on the Mound, St Andrew's Square, George Street, and is 1 min from Waverley station.
With it being so close to Waverley, we did hear some station announcements but they weren't loud and intrusive, and they had stopped between 11pm and 8am.
We booked a 2 bed apartment but ended up in a 3 bed which was a nice surprise. The apartment was huge, it was clean, well equipped in all regards, especially the kitchen. The only suggested improvement would be a Nespresso machine or similar. You can buy barista made coffee at Tue reception which we did each morning.
The beds were comfortable but it was an adjustment going back to a double after 16 years in a super king at home!
The apartment was so big I played a very long game of hide and seek with the kids which was great fun! 2 bathrooms were helpful too with kids taking an age to do anything!
If you're looking to explore the best of Edinburgh with a bit more flexibility than offered by a traditional hotel then we fully recommend Princes Street Suites.