Yes, you can use points for a category 3 cabin. It is not listed on the point charts but is available from member services. For the July 24th Eastern 7 night cruise, it is 541 points per person. I don't know the point requirements for the 3 or 4 day cruises. One disadvantage is that the reservation is subject to the 11 month window similar to other disney collection trades. Very often, the category 3 cabins are fully booked by that time.