This may be very naiive, but what does a Concierge and Butler do for you that you do not get in a basic cabin?
I have a Penthouse on the Norwegian Dawn in January, but have no idea what to expect from them.
The concierge performs the same services that he would in a hotel. Mostly making reservations, coordinating activities away from the ship and generally finding out things and answering questions. They take great pride in never being stumped.
A butler makes your dreams come true. On a ship he will probably be responsible for more than one suite, but you will never know it. They will unpack, press, serve you in your suite, keep the nibbles and drinks coming, smooth the way to the theater or dining room, you name it. Unless you are used to being supported by the service trade, you probably won't take advantage of half of what he has to offer.
Best approach, tell him you've never had a butler and ask what he can do for you. He will appreciate your honesty and give you far better service than if you try to bluff it. He has seen it all. Insult him and he can make you wish you hadn't.
Thought it was a nice touch when the ship next to us got underway, guests with suites had their butler standing in the background as they waved goodby to us lessors.
I was on the Dawn and had a Concierge. She booked any shore excursions, was able to get us a tour of the galley with the chef and handled any problems which may have come up with anything in our cabin. Actually we only had one request with the cabin and that was not fixed! The room steward opened the sofa bed every night but it blocked our exit to the balcony. We requested the bed be left folded and we would fix it when we were ready to go to bed. However, the steward said he HAD to fold the bed down or he would get "in troyble" with his supervisor. No real problem because we just folded it up ourself.
The concierge also makes reservations for alternative dining and can order your bottle of wine for dinner.
I'm sure the list is longer but we didn't really use the service very much.