The Rotterdam is the newest ship in the fleet with all of latest bells and whistles, you may not enjoy the older ships after you have been on the Rotterdam. What type of cabin would you book? If you are thinking about one of the longer voyages, perhaps you should sail a different itinerary on a ship in the same class as used on the longer voyages. I don't think any of these ships are used on the longer voyages. The ships used on the longer voyages are older and there are not any balcony cabins that are not the more expensive suite cabins.
Good Luck