This is the right decision, based on how you described yourself.
As to the butler, I think it varies very much by cruise line. On Norwegian, the butler is a person who is going to deliver the room service and can work things out for you with restaurant reservations or shore excursions--kind of a concierge-type person.
On a more upscale cruise line (e.g., Silversea), the butlers are actually trained to be butlers. That means they'll unpack your shit and put it in drawers or hanging in the closet when you arrive. If you can't tie a fucking bowtie (I'm telling on myself here), they'll help you out getting dressed for a formal night. If you need gifts for the office, they'll run into town during a stop and pick up a bunch of shit from a local shop (I might be telling on myself again). If you have a question and you don't know whom else to ask (e.g., "I want caviar on the table here every evening at 5:30--is that doable?"), you ask the butler. And the night before you leave, you can have the butler pack you up while you're at dinner (and they do it with very nice tissue paper--much better than I've ever packed myself).