I took care of the employees who deserved a little extra when I checked out of La Amistad.
Generally speaking, I review checks in Latin America to see that this the standard 10% is included. If not, I will usually tip the standard 10%. If the tip is already included, I usually don't tip extra unless the service is above and beyond. If the meal is exceptional, I will thank the chef and give him or her a propina.
My wife and I stay at a number of AI resorts in Latin America. When we arrive, my wife turns on her Colombiana charm (starting at the reception desk), and manages to connect with the hotel staff right off the bat. The result is: we end up with enhanced services and make new friends along the way. This helps, especially if one intends to return to the same resorts. I trust my wife's judgment, and let her manage the tipping. "Pay Day" starts the day before our departure. At the resorts we stay at in Cancun and the Riviera Maya, individual members of the resort staff will hand you a card with their name and job title, and ask that you mention them by name is your Trip Advisor review. Sometimes, it's hard to figure out how to mention 12 different names in a review.
