Stayed there last summer on a company paid trip - we took over the resort & everything was included, so my experiences may be rather different...
The Four Seasons car or van picks you up at the airport. I'm guessing about a 15 minute transfer to the hotel. I hate to say, but there's not a whole lot for your daughter & friend to do other than lay on the beach or by the pool. I take it they have an excellent children's program (no kids were allowed when I was there), but I'm not sure what girls of this age would do. There's no shopping or going to town or much getting away from the resort & exploring. There is sailing off the beach & a beach resort crew. What kind of accommodation did you book? The beachfront villas are nice. If you have a regular room, be sure it's on the 3rd floor & check out the view before you accept the room - some of the villas block the regular room's view. There's a more casual screened restaurant with ok to good food & an upscale Italian, which I thought wierd - last year they weren't that well trained in what upscale Italian restaurants should provide, but the food was good & the wine very expensive. We liked the beachside bar a lot & spent many hours there

The spa is excellent - real Thai masseuses, who are charming. I did the 'jump-up' aerobics class, which was fun. We did a day sail to a little island we moored off of & snorkeled - I've experienced much better snorkeling, but at least the coral was alive & there are fish. Golf course is good, but long & narrow. It gets very hot out there, so plan for an very early tee time. Did not play tennis. People complain about the exercise room, but I liked it. There's also a small pool & private jacuzzi off of the gym area. There's an adult pool, which I appreciated. TONS of mosquitos - be prepared - they provide OFF in every room. Also large black moths that look like bats - never seen those before... It is a beautiful resort, but very very expensive (even with basically everything included except the day we came in early, we had a pretty big bill checking out). The staff are very sweet, but probably not the highest caliber of service - there were labor problems that hit the front page of the local paper when we were there, but we were not aware of them. I think it's great for a couple to chill or a young family, but, having a 14 year old girl, even with a friend, I think she'd go bonkers with boredom here. I really think I'd pick Atlantis (SHUDDER, but I believe there are some more upscale places to stay there...) if I were taking our daughter there. Sorry. Again, I was there under different circumstances...