Letter from your employer
Bank statement
Itinerary
Hotel bookings (confirmed)
DS-160 form
Just be what you are (natural), don't show off, don't make things up and lie about anything. Just answer visa officer's questions truthfully. Don't wear a suit, just go in casuals; a lot of people wear suit like its a job interview. He didn't see a single document, not even hotel bookings or bank statement or employer's letter.