I have cruised with my son at age 8 in the Caribbean (Royal Caribbean Monarch, 2500 passengers), husband and son when he was 12 to Turkey, Israel & Greece (Renaissance, 500 passengers..now defunct) and then last summer when my son was 17 in the Baltic (Celebrity Constellation). My son read a lot when we were at sea with Renaissance, but had a great time anyway. Royal Caribbean seems to have more activities for younger kids; I note that the newer ships have minature golf and climbing walls. But, the younger kids last summer on Celebrity (only about 8-10 of them in the younger range) seemed to be having a blast. I saw them all over the ship, pretending to be pirates with a group leader and on scavanger hunts, etc. There about the same number of kids in the middle years and about 20 teenagers. We are going to Alaska this summer on Celebrity Summit with my sister and her two girls (15 and 13) and likely a last cruise for a long while with our 18 year old high school graduate. Kids really enjoy the freedom on the ship. There is a video game room, and a play room with a separate kiddie pool on the back of the ship on the Constellation class ship. Have fun.