Off the top of my head...
I generally leave a partial tip (perhaps half of what I'd leave for the full week) for the maid after the first night of a stay and then the rest of the tip at the end of the stay.
Waiters, yep. 15% to 20% of the pre-tax bill amount, depending on how good the service was.
Concierge attendant if they actually do something for you - giving you brochures or discount coupons doesn't count for me, but if they make a spa appointment, get tickets for a show or that type of thing then they should get a tip. Depends on how far out of the way you think that the concierge had to go to satisfy your needs. Generally, $5 to $10 should do it.
Valet parking attendant. Some people tip both the key attendant and the person who takes/gets the car for them. I tip a few dollars to the person who takes the car and person who brings it back. $3 to $5.
Bell hop. If someone takes your bags to your hotel room you should tip them. Same thing if you have someone pick up your bags when you leave. $2 or $3 per bag.
Curbside luggage attendant at the airport. If you take advantage of the curbside bag service you should tip the attendant. $2 per bag.
If you're using a taxi or car service you should tip the driver. 15% to 20% of the fare.
Anyone in the service sector who provides a service for you - hairdresser, masseuse, babysitter and such. A percentage or flat amount depending on the type of service. Unless you're going to use them again during your stay it doesn't have to be a lot.
Dick Taylor