Top tips would be -
Avoid beach at weekends as get overcrowded, local tourist's favourite beach too.
Drink water all day long to avoid getting dehydrated (you may do without even realising especially if drinking)
Buggy shade a must - I prefer a canopy and a buggy that lays flat for sleeps during evening meal
Take a boat trip - sound's corny but would recommend the Shirley Valentine boat trip - walk out towards Penera from the beach front - lovely couple English lady and Greek husband with a little dog called Keo great with the kids - my DS got to steer the boat and still talks about it 2 years later! Ok to take buggy on board
Enjoy a meal at Island Affair - but all the restaurants great and brilliant with the kids.
There's a little adventure park at the end of the main road where you can buy tokens which is open at night - used to be a good bribe
Water show is very good but we never been because my youngest was too little and always asleep when it started.
Break the flight up by having bits and bobs in a bag to do. Small slide and scribbler good (saves losing crayons under seats), magazine with freebie on the front, I even took a small pot of playdoh once and a few small cutters in a plastic bag. Save a surprise for the last part of the flight as it's 5 hours but goes quiet quickly after the meal. Hopefully they might sleep a bit or even better meet a friend nearby.