I will give you the best bit of advice you will get stay off the jet skis they are the biggest rip off they will claim you damaged them
they are all run by the mafia and the policeare the mafia so you wil lget no help there
that would take you to flights to get from chang mai to Phuket I would just do kanchanburi rather than chang mai
hell fire pass in kanchaburi is a must see was worn out just walking god knows what them poor souls put up with
chang mai is a long way away 12hour train journey and after the trip there most wont wantto travel to much further
so at a guess I would say at least a 3 week hol depends on how long you want on the beach I guess if I were you I would go to kanchanaburi as its only 2 or 3 hours from Bangkok then
that where the monk take the tigers in that worth a visit too Theres also a hot spring there that is worth a hours stop
the bridge over the river kwai hwll fire pass is a must see up there Kanchanaburi is worth a two or three day visit the nice to have a meal and a drink on the river Also if...