Tipping on shore excursions (or otherwise...)

[Bug'sMom]

Okay, help a novice out.... I know that it is customary to tip your shore excursion guide but how much is expected per person? I know, I know....it depends upon how long, where, what kind of service BUT just generally speaking, how much would one tip let's say on a tour to Stingray City or Dunns Falls? Do you tip the hired tour operator and then the actual guide that helps you climb???? Do the taxi drivers expect a tip every time you get in their cab? I am posting this on several boards because I would appreciate as much feedback as people are willing to give....(P.S. I also heard that you should tip whoever handles your lugguage. THAT could get pricey! (If you consider how many people handles them from the airport on.....)

 

Many, many thanks!