Anyone know if it's possible to hire a plane and instructor in Kos. Looking for a day away from the beach and kids during this summers holiday! Cheers

I have not seen any light aviation on Kos apart from visiting aircraft however I have not been there this season.

One option is to contact the Rhodes based schools/aeroclubs in case they can meet up with you at nearby Kos for a flight.
Check for LGRP based operators here http://hellasga.com/links.html

Other option is to contact John Chaskakis who has based aircraft in Kos and some CFI/Examiner licenses, email haskair[at]yahoo.com
I have not communicated with him for ages and I don't know if he still operates from Kos with his Piper Seneca.

Additionally for an other Cessna based in Kos contact aviator[at]freemail.gr