The one time I had a massage the girl spent the whole time pressuring me to buy their products and they aren't cheap!
Had a lousy over-priced hair do, manicure and pedicure so will never again give my money to Steiners. I get the same things done at home for almost half the price they charge.
HWH - if this is what your sweetie wants, then by all means, book the Spa as soon as you get on board. Have a great cruise and a lovely honeymoon.