We have just returned from a stay at PBH and have stayed at HRH twice before. We have eaten at most of the CityWalk restaurants, and whilst I agree that NBA City and Nascar Cafe are good bets for teenage boys, there is nothing to compare with Hard Rock Cafe, IMHO. Great venue, good food. Take your teens there - I promise they won't be disappointed.
Our teenage girls loved HRH, btw - within walking distance of everything which gave them great freedom. They loved the Motown Cafe because they got to get up and dance.
We love the Palm at HRH - superb steaks (and lobster) if that's your bag, but I agree that it's not necessarily the best place for teens. It's expensive.
Mythos is good. Very good. But, at the risk of sounding pompous, those who say it is fine dining in a park, do not understand fine dining. Go there for lunch if you want something 'bistro style' and above average for lunch, but don't go there for dinner expecting fine dining. It that's what you want, book ahead at Emeril's, Tchoup Choup or Delfino Riviera.