As your children are that age I would suggest Royal Caribbean Liberty of the seas sailing from Southampton next summer, worlds largest ship and brand new. Lots and Lots for teenages and lots and lots for you also.
I think cruises are not for teenage kids better with a hotel holiday abroad.
Our children are now 16 & 17 and we have cruised with them since the age of 5. They love it. Princess cruises have excellent teenage facilities and also offer alternative dining so they an choose to dine with you or their new friends.