A 10% to 15% service charge is added to all hotel bills, though it doesn't always go to staff.
It's usually expected that you will tip more -- $5 per person per day for the housekeeping staff, $20 for a helpful concierge, and $10 per day for the group to beach attendants. It is not uncommon to tip more generously, particularly at higher-end resorts.
Many restaurants include a service charge of 10% to 15% on the bill; it is your choice to tip more if you feel the service is deserving. If there is no surcharge, tip about 15%. If you have taken most meals at your hotel's dining room, approximately $100 per week can be handed to the restaurant manager in an envelope to be divided among the staff.
Taxi drivers should receive 10% of the fare.