General Tipping Guide:
It is customary to tip while receiving services, here is a general guide that will help with different situations you may come upon.

Doorman:
The doorman will usually receive $1-$2 for getting you a taxi, and opening the door for you. If you are just arriving, storing your car and/or have baggage which he or she is helping you to retrieve out of the car, he generally receives $.50-$1 per bag dollars for that service, since he will place it on a bell cart and bring it inside for you as well.

Bellmen:
When luggage is stored, people generally do not tip. However when you go to retrieve your bags, it is customary to tip $1-$2 per bag generally no more than $10. So if the poor bellman is asked to retrieve 3 bags for you and you give him $1 that's usually frowned upon, giving $2 is better if you are really strapped for cash.

Restaurants:
Every time you dine at a restaurant, you want to tip the server 15%-20% of your final bill. If service was horrible, you can tip less. Review your bill as some restaurants may already include a "Gratuity" charge, especially if you are having a "set" meal, or have a certain amount of people.

Room Service:
Room service usually has a gratuity included in the price, check the receipt carefully for this. If there is none, follow the guidelines of a restaurant you may want to include a little extra if a delivery charge is not included as well.

Housekeeping:
The person that cleans your room for you everyday is the housekeeper. They work hard to make sure your beds are made, the garbage is taken out, and the towels are re-hung or refreshed if you asked them to be. A tip of usually $1-$5 per night, up to $10 a night, depending on the mess that you leave is generally left on the desk or night table when you checkout, or left in an envelope marked housekeeper of room (the room #) and given at the front desk.

Concierge:
If the concierge helps you to book a restaurant that was hard to get, a $5-$10 tip is nice as it may have been his or her connections or persistence that got the reservation made.

Front Desk:
Generally no tip is given for checking in as none is expected, however if you were bugging the Front desk staff for something "Special" i.e. you had a Queen bedroom reserved and they were able to get you into a 2 Double room even though they are out of them, giving them a $5-$10 tip is a nice gesture but not necessary, same goes with complimentary upgrades.

Maintenance:
Maintenance generally does not receive a tip for fixing anything in the room.

Request for items:
If you place a request for items, i.e. pillows, an iron, a fridge, a rollaway bed, etc… The general guide is $2 for small items, $3-$5 for larger items, with a minimum of $2.