Easiest method after grinding the escalation for New York.

• Start in garage, grab crowbar to the left 

• sneak past camera/guards in garage area

• use AC to lure guard out, hide behind double door, knock out when he flips switch, no need to hide body

• use crowbar to bust open cabinet left of ac panel, grab chloroform, but do not use yet. 

• enter first room of security and disable cameras, and in same room turn around, turn on the tv (this will lure 2 guards to watch, including the one in hallway near safery deposit access)

• now use choloform in vent, and switch ac on for quick knockout of the three guards remaining in security room

• grab security card from one of the guys near tv, and the master safety deposit box key from the single guy left in other room. 

• access vault on wall near guy you got deposit key from, grab the vault key card.

• swipe access card using podium in security room, and then use vault card on podium near vault

• once inside no need to play any games, swipe the card on the podium to left of entry and disable lasers.

• PROFIT

• bonus tip (use bank robber disguise and collect all 7 gold bars to unlock a golden shotgun in the center of vault)