Rule of thumb is to tip anyone who has it in their power to do something helpful for you.

If you arrive by taxi or limo, that driver will expect some sort of tip. The amount varies widely but can go as high as 15% or more. Your hotel can often recommend a "car service" that may not cost much more than a taxi, and will be a much better experience. Ask them ahead of time and find the set price for the price from and back to the airport.

A $20 tip at to the front desk, at check-in (discretely) has amazing power to produce an upgrade, for example.

The hotel's concierge will expect a tip for booking you a dinner or show reservation, and should be providing some sort of value - getting you into place that is usually sold out, getting you a good table, etc..

The bellman will expect something on a per-bag basis if he takes your bags from the car to your room.

Tipping at a restaurant is typically 15% of the bill (before or after tax) +/- unless it is explicitly included on your bill already.

Tipping for drinks at a bar can be the same 15% but is often much less. More for making a complicated cocktail compared to opening a beer, for example.

Any room service for meals or massage etc will typically have a gratuity built into the charge and will typically be described as such - nothing extra is required.

If you are having Tennis lessons or something like this at the hotel, some sort of tip is expected.

Tipping your maids daily or at the end of the stay is done by some people but is not really customary nor is it expected. $5 per day unless it is a huge suite is fine for something like this. Leaving money out on a table may be mis-interpreted as a tip so be aware...

Tips in cash are always preferred to a room charge. If your travel is reimbursed or your access to currency is limited, however, go the room charge method.