Jacqueline, is this for your upcoming cruise on Norwegian Spirit? If so, the AC stateroom (categorized as a Penthouse by NCL) will also offer a whirlpool tub, plus butler and concierge service. Additionally, you get VIP services such as priority embarkation and disembarkation, priority tendering, and special events such as cocktail parties.
I haven't had butler service on NCL, but we have enjoyed the concierge service and some of the VIP perks on a different NCL ship. Our concierge stopped by daily to make sure all was well, and to find out if there was anything special we needed. She also made our reservations to the specialty restaurants, and provided tips and additional information on shore excursions. Yet, the cabin did come at a price. Whether it's worth the extra $ is up to you.