NO DUTY FREE-FOR-ALL
Don't let them spend all their money before take-off. Teenagers are suckers for airports. Steer them away from the electronics and gadget shops and remind them that there will be lots of far more interesting stuff to buy when you get there.
BRIGHT LIGHTS, SHORT FUSE
Book somewhere central and lively, or at least close to shops and cafes. Teenagers don't walk much and their mood plummets if they're hungry or tired. You don't want to be stuck in the middle of nowhere when that happens.
BE PREPARED ... TO LIE
Don't sit at breakfast staring at a guide book and asking for their opinion on what to do. They will go all droopy and say "No" to everything. Pretend you have a plan. Take their amendments so they feel they had a hand in the day.
MASTER THE ART
If you want your teenager to do a museum or gallery, suggest you do two or three in a row. Then, with a sigh, agree that maybe one is enough. Result! You never wanted to do more than one anyway!
SET THEM FREE
Let them explore without you. Sit in a café and try to relax while they walk around for 20 minutes. Synchronise watches, agree an emergency plan - make sure they know the name of the hotel and have money for a taxi.
Make sure they get plenty of time in the hotel room. Cable TV (but watch out for the sex channels), room service, beds made for them - these are all luxurious novelties to teenagers and should not be missed.
You want to know the secret of how to get a teenager up in the morning? Lie. Tell them the hotel stops serving breakfast at least an hour before it really does. That'll get them up.
Don't EVER tell them that anything you want to do during your trip is "interesting". Your kids aren't stupid. They know the word is just a euphemism for "educational" and it's the ultimate teenage turn-off.