We cruised on NCL when my daughter was almost five years old. She had a great time -- the youth counselors were lots of fun. NCL is good for you since it's one of the only two cruise lines which accepts children as young as two years old in its youth program. As for the teens, since my daughter is now only 9, I don't have first hand advice. Maybe you want to post a message on the teen section of this message board to see if any teens who have sailed on NCL have any advice for your teens.
Bermuda is a lovely family destination -- swimming, snorkeling, botanical gardens, swim with the dolphins, maritime museum, etc.
Luisa Frey Gaynor
Family Cruise Editor