We are actually doing one night here during our April trip. We are staying on Disney property (Ft. Wilderness Cabins) for 10 days, but are double booked for one night in the middle of the week at the Nick hotel. My daughter really wants to do the character breakfast (she saw pictures from when my nephew stayed there last year) and you can only do the character breakfast if you stay at the hotel. We don't want to check out of our cabin and check back in, so we are paying for two rooms that night (and we're paying full price - no discounts). So, I hope to do as much as possible to make it worth it. Anyway, I think if your kids like the Nick characters then this would be a fun night for them before the cruise. I hear the pools are great and from what I understand there are arcades, shows, etc. You could also book the breakfast for the morning before you check out if they are interested in that.
Have a great trip!