When you first enter the casino, you can pass a speech check with Swank, allowing you to enter with your weapons.
Next, if you were able to pass the check and were able to keep your weapons, go past the front desk, across the casino floor and straight to Benny. Immediately he will turn around and greet you. Then you will start to have a conversation with him. You will have many options when you first begin to converse.
You can do the passive route and follow the responses leading to him giving you the suite key and asking you to go up and wait in the room.
With a successful Speech Check you can get him to lead you to the penthouse, which give you the option of killing him without his guards. You then get the Wildcard: Ace In the Hole Quest Option, and can proceed to his personal suite, to meet Yes Man.
The other route is to directly attack him . He yells for help from his 4 bodyguards and himself. Two of the guards will be carrying Silenced Submachine guns, the other 2 carry silenced .22 pistols, and Benny is using Maria, a unique 9mm pistol. Afterward, collect your treasure from the dead bodies and move to the suite.
If your character is female and has the Black Widow perk, she can convince Benny to have sex with her in his suite, upon finishing you have the option of murdering him in his sleep.
If you choose the passive route, go straight up to the presidential suite. Once in the room, check around for clues, grab whatever items you need, and return to the door, where Benny will be on the intercom. With a high speech you can persuade him to give you information. Otherwise, you will end up having to threaten him, then his guards will show up and attack you.
Find the safe behind the counter and take it, once you have, Yes Man should confront you, talk to him to activate another quest.
The phrase "ace in the hole" is used to describe something that can supply a sure victory when revealed, which specifically refers to casino blackjack, where the dealer's second, hidden, face-down card is an ace. When the visible card is a ten, or facecard, the dealer will check the hidden card through a hole, containing mirrors, which will show if the "hole" card is an ace.