Istanbul pretty much covers everything from museums to galleries to clubs ......
Depends what your teenagers are in to and what they like doing. If lying on the beach and doing nothing is there preferred thing then head to Bodrum or similar, if its culture then mix Istanbu with Cappadocia and throw in some adventure activity such as paragliding? about 6 years ago
I think Capadoccia is one of the best places in Turkey ofcourse in the World where you can visit spectacular places allaround the Turkey.I hope you know that the most of the beautiful places in the world are in Turkey and Capadocia is one of them.I suggest you some places in Turkey where i had been to.
Goreme Open Air Museum
Kaymakli Underground City
These are the cities you must visit.
I hope you have a great holidays in turkey.
These are some suggestions from my end.Have a great holiday.I suggest you to go through this link for wholesome tour packages http://www.middaytravelturkey.com/ about 5 years ago