I'd also vote for maximizing time in Istanbul. The language barrier is a non-issue. The public transport is excellent starting right from the airport.

As a grandmother, I felt totally safe wandering about. Very kindly treated and didn't encounter any scams. Fairly aggressive salespeople, but they were cheerful when I firmly declined. They simply moved on to the next potential customer. I wasn't bar-hopping late at night but I understand simply staying aware and using good judgement will take care of one in that circumstance.

Trying to see three cities involves a whole lot of moving one's body and possessions, checking in and out of hotels, and other time wasting.

I spent a couple weeks there. Never ran out of things to do. And would go back.

There is a visa necessary, but it is a non-event of standing in line at the Istanbul airport and handing them $20 US.

IMHO - Romelle