It should always be handed to the person directly. Never leave it around. Never give cash or chips. It could be considered a bribe. Never tip in any other situation.
Most hotels now offer professional childcare to their guests.
50-cents at nickel slots. That way your cost of tips for drinks is halved. Or pay nothing because you have been comped. Realize that even though the meal is a bargain, you are getting full restaurant service. If the service was satisfactory, tip based on the value of what the meal would normally have cost instead of what they actually are charging you.