You need a valid passport.  US citizens would need an entry visa to Turkey which I will gladly get for you.  You’ll need to bring/send your passports to me, then I’ll hand carry them to the Turkish Embassy and get your visas.  They cost about $40.00 (this was the price last year), which you can reimburse me for, upon delivery of your visas.  No other documentation is required.  

You are welcome to get your individual visas yourself.  If you live far away from my location, which is Falls Church, VA, you may opt to take care of the visas personally.  In this case, please take or send your passports to the nearest Turkish Consulate and request your visas in a timely fashion.  In case this is not possible, entry visas may also be obtained at the gate of entry.  There is no price difference, but it saves us considerable time to have our paperwork complete upon entry.