We spent a few days in Edinburgh last year. We stayed at the Double Tree Edinburgh City Centre on Bread Street. It was a short walk to the Royal Mile, Edinburgh Castle (you could see the castle from our room) Calton Hill, Arthur's seat, New Town, Grassmarket, etc. Not sure how much you enjoy walking, but we walked it with no issue.
Grassmarket has lots of pubs and cafes. We stopped in a few for drinks but they were nothing special. Plenty of beer and mixed drink options. I drank Tennents and Guiness when I wasn't drinking Scotch. Someone on this forum mentioned El Cartel. It has Tex-Mex type street tacos. It was good but nothing to write home about (we did meet some other Aggies there so that was neat). The Hanging Bat (a very short walk from our hotel) that had some excellent Haggis fries and were very excited to meet Texans.
The Piper's Rest is another pub off the Royal Mile (in Hunter Square) that had decent enough pub food but also has a drink called the Weedgie Mule made with Irn Bru syrup. Too sweet for me but the wife enjoyed it.
I would suggest buying tickets now for any castle, palace, etc you may want to visit. They say they sell out during the summer time. We bought about 4 months in advance for Edinburgh Castle, Holyrood, etc.
Arthur's seat is great. It is a moderate to stressful hike but well worth it when you get to the top. There is also an old church (the name escapes me right now) that we detoured to on the way down.
Lots of shopping on the Royal Mile if that is your thing. Most shops all have the same or similar things though.
We didn't see all of Edinburgh by any means but I think we did pretty well for 2 1/2 days.
Double Talkin' Jive...