Thank you, your replies most helpful we had already decided to give Naples and area a miss. Nice to know about the possible discounts!
The GP will normally have it's Formal night on the evening of a day at sea - reason being the length of time some la----, sorry people take to get ready. That means you won't get any discounted prices at the spa ( only get them on port days ) Hope this helps.
PS - Take a tip from me unless you are going on an excursion or doing your own thing to Capri , Amalfi Coast or Pompei just give Naples a miss ( you're not missing anything and you won't get run over) and stay on board and book that treatment at a discount price and relax.............