CountryGal, I am a licensed Aesthetician, so maybe I can help you somewhat.
Some things to consider before you book off-ship are price, quality of products used, and the length of treatment time.
Have you asked the Windmere what line of products they use in their spa? Have you researched the product line for Majesty?
There is a convenience factor to consider when you book on the ship.
Atlantis is a great way to spend time while in the Bahamas.
If you find out the product lines and you would like an opinion, I would be glad to help you.