Bellmen: $1 per bag
Cigarette Girls: $1 per smoke
Cocktail Waitresses: $1 per drink
Dealers: There isn't a general rule to tip dealers. Periodically placing a bet equal to yours for the dealer while you're winning will suffice. If you're playing a "carnival" game like 3 Card Poker and hit a jackpot, you may choose to throw a chip or two back to the dealer each time.
Front Desk Attendants: If you're looking for a complimentary upgrade, $20 is a good place to start. Check out thetwentydollartrick.com to learn more.
Hosts: Generally, tipping hosts is done by gift as most won't accept cash. If you know your host well, pick something that you know they'll enjoy, i.e. a specific type of wine or chocolates.
Maids: $2-$5 per day
Photo Ops: If you're taking a picture with a Transformer or Buzz Lightyear, the people in costume are going to expect a tip of at least $5.
Room Service: 15%-20%, if not included on the bill. If it's on the bill, a few extra bucks is nice for good service.
Slot Attendants: There's no typical tip here for when you win a jackpot, but something is expected. The amount will be different depending on the jackpot, but somewhere between 5-10% is usually considered a very good tip.
Taxi Drivers: Love 'em or hate 'em, taxi drivers are providing a service. 15% should be sufficient if they're not long hauling you.
Ticket Writers: These are the guys at the sportsbook that take and pay you on bets. Tipping philosophy seems split 50/50 when it comes to tipping on normal bets. If you win a huge bet, you'll probably want to thank them with a small percentage of the winnings.
Valet: $2 when dropping off and $2 when picking up.
Waiters/Waitresses: 15%-20% depending on the quality of service you receive.
This writer always gets singles when he cashes out at a casino to ensure that everyone providing good service gets a thank you. All of the tip amounts above are just guidelines so you know what your service providers are expecting. These aren't hard and fast rules because we know that tipping is a personal choice.