My wife & I booked Mehmet for an 8 hour tour of Istanbul. He catered to our needs and ability very well.  We enjoyed his company, demenour, and ability to tell us about the sites that we saw in Istanbul. It was up to us to decide what we wanted to do, with Mehmet suggesting possible itinieraries. 

I found it particularly comforting when going for lunch or going to the grand bazaar that Mehmet doesn't have an agenda; if he does have relations with the vendor, he'll tell you ahead of time, else he'll help you haggle (like he did for us at the grand bazaar) and reassure you that you have the freedom to walkaway.

I would highly recommend a tour with Mehmet if that was an option for you.