Hi, haven't stayed in chrousso, so cant help with the kids club.
I have however been to the Beach at Palliouri to go on a boat trip and the beach looked nice and quiet with Pedaloes available to hire.
If you are going with First Choice, you will be offered a number of excursions including boat trips and trips in to Thessalonika City and a few Historical places.As a family we have done the Pirate Boat Trip which is good fun as you spend most the day at sea stopping of at two Islands to swim or snorkel if you wish. I even walked the plank and jumped into the sea the two times I have been on this trip. I can highly recommend this one and the captain is a good laugh.This trip is not a Adult orientated trip like the sunset cruise its one for the whole family.