Hi Karen,
I also have 3 children, they're aged 14, 11 and 3 and the older two pleaded with us to book again for the third year running !
Im sure you'll love the koukounaria [ just budget for the hire cost of appliances/air con] Of course you always meet the serial complainers on holiday who pick faults with just about everything and anything but we really cant fault the apartments or the resort.
Alykes isn't over 'touristy' which is why it's suited us since our youngest was one year old. You'll be hard pushed to find locals as friendly anywhere.
There is water sports on the beach and im sure there are also water sports in alykanas [ a short walk from alykes] although i stand corrected if im wrong !
The 3 pools in the Koukounaria are ideal for the kids although i dont think there are any tennis courts locally ? [ im not being much help here am i ?

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I would reccommend booking a day at the water park, there are plenty slides for the older ones and lots to entertain your youngest [ just pose when you're on the lazy river as photographs are taken when you dont realise and posted on a board for you to buy .... After bearing 3 children .... mine was horrific !!

enjoy your last minute packing [ its frantic here !]
Hayley