Assuming you are staying at the South Point...............
ATTENTION: This is not a post condoning or encouraging gambling. If you do gamble at the South Point during your trip and use your card, be it table games or slots, you have nothing to lose by asking at your day of departure if they can comp any or all of your bill including any food you might have charged to the room. So may people leave Vegas and never ask for anything when they would be given comps with a smile.
For you poker players make sure you get a "poker room card" and use it every time you play poker and you will get minimum of $1/hour in comps.
To sum it up if you do not ask you will not receive what you have coming to you.