Ocean village will be fantastic for you age group. Informal, friendly and fun- just don't go at Christmas- too many kids!
To be honest most ships/lines fit that bracket providing you keep away from school holidays. Even the most child friendly ships have never been a problem to us, as we steer clear of those periods & the price is also very often considerably lower as a result......Wilba.
Try Celebrity best time for prices Jan -Feb if you go into March you start to get into there spring break and they send there College kids or then at the end of the year it gets cheaper.Go onto there web site pick a ship and itinerary you fancy go to the booking section and price it up, then ring round the agents to get the best deal? hope it helps.