Calica is a gravel pit... seriously it is. So from there you can catch a cab to Playa Del Carman which has all of the places to eat, beach and shopping. You can also go to Xcaret (Eco park) which is wonderful. No need to book excursions for either. When I was there, cab ride was 15 minutes from either and cost $10.
Life is too short to let the ship of your dreams sail without you.
Carnival Destiny Feb. 2006
Carnival Fascination Feb. 2007
Royal Caribbean Grandeur of the Seas Feb. 2008 The DTW & MsBJ tour
Carnival Valor MsBJ and Dina Feb. 2009
Carnival Glory MsBJ and Dina Feb. 2010
Carnival Dream MsBJ and Dina Feb. 2011
I second the suggestion above that said to grab a cab and go into town. Calica really is a gravel pit, we were shocked to find that this was true. There are a few vendors right by where the ship pulls in, but we found them more expensive than those that were in town. Our first trip here we took a cab to the ruins and the second time we went into the town to shop. The beach here was also very nice and we enjoyed the cool off in the clear water with the nice soft sand. Whatever you decide to do, I honestly don't think you'd need an excursion here.
__________________ "Faith is to believe what we do not see; the reward of faith is to see what we believe." -- Saint Augustine
Carnival Paradise 2000, Carnival Paradise 2003,
Carrnival Victory 2004, Carnival Valor 2005, Carnival Fantasy 2006, Carnival Fascination 2006, Carnival Destiny 2007
Carnival Sensation 2007. Carnival Fascination 2007 Carnival Triumph 2008, Carnival Fascination 2008, MSC Orchestra 2008, Carnival Fascination 2009, Carnival Glory 2010