If your tour doesn't get finished until 9, I don't know how many shops will be open after that. I would stay closed to the cruise port. All is within walking distance, but I have read that it is not safe to go up over the hill at night (you will see what I mean when you get there) to the areas between the two forts. The two forts are the absolute best, but are only open 9 - 6 December thru May. Since they are a National Park, go to www.nps.gov/saju for more info. The Sheraton has a casino & there is a Senor Frogs behind the Sheraton that's a lot of fun. There was a locals bar close by called The Brickhouse that we also had a lot of fun in. I hope you love OSJ as much as we do - the history and architecture is awesome.
Sovereign of the Seas (Bahamas) 8/1998
Carnival Paradise (Western Caribbean) 6/02
Carnival Destiny (x2 Southern Caribbean)1/05 & 1/06
Crown Princess (Southern Caribbean) 1/07
Victory (Southern Caribbean) 01/18/09
Carnival Liberty (Eastern Caribbean) 02/05/2011