Yes, there are stairs. We stayed on the 4th floor three weeks ago, and we often took the stairs vice the elevator because they were often more convenient. We were in 2415, which put us exactly diagonal to the elevators across the open foyer. The stairs, on the other hand, were just out our door and to the left.
If you're in the parking garage, the stairs are located in the second alcove that does not have the elevators. If you're in the lobby area, walk toward the Wind and the Waves but instead of taking a left to get to the restaurant, take a right down a small, short hallway. As those stairs undoubtedly butt up against some guest rooms, we made sure to not be too loud in the stairwells which, of course, are mostly cement and metal.