Rocker helps keep your tips out of the snow, thus providing better float.
There are a number of skis that would fit what you're looking for. Armada, Line, ON3P, Atomic all make skis that fit what you're looking for. For a pure pow ski I'd look for something 120+ width underfoot but there are skis that are 110-115 underfoot that will still rock pow with a bit more hardpack performance.