You could call CR to find out, but we were there this summer and I think the roof is only for Cal. Grille diners. We did that one night and it was nice. We did view them from the outside stairs on the Magic Kingdom side of the CR one evening. It was nice, but I don't recall the music being played.
One morning I hiked up the outside stairs to the roof (MK side, front of bldg) and got on the roof. What a view! Took some great pics of Poly, GF, and MK. You can access the stairs from the lobby or from any floor I think.