I am on that cruise and was just planning on bringing two dressier short dresses. I would doubt we'd see many full-lengh gowns. Hubby will be in a dark suit and boys will be in navy sportcoats. Fun, fun, fun! Can't wait!
On a 7 night cruise I think you will see more longer gowns than you do on shorter cruises. Your dressy short cocktail dresses will be fine though. The spa has many different types of treatments facials, massages, teeth whitening, ionithermie. They run in the range of $109 to $199. They have specials on the first day and on port days. A treatment like a Lt oxygen Lifting facial is $109 but on port day is $79. I recently had a mini facial (25 minutes) on the Fascination for $29 on port day.