I ended up going to Izmit, Turkey back in 2000 and had a couple of opportunities to come back to Istanbul for day trips. Trying to stuff a couple weeks worth of sight seeing into a couple days makes for a whirlwind tour. In Istanbul you'll want to see the palace Topkapi Sarayi
. You can have a meal there as well. The Basilica Cistern is a must do as well. The Blue Mosque is the mosque to see in Istanbul, but we never made it to it. We went to some others and they are quite impressive structures. So much history is there. The Grand Bazaar is equivalent to an open air shopping area where they have a variety of most local items.
Take cash when touring around the city, the rest rooms took money back in 2000 and they were very few and far between! Guys and gals used the same facilities in lots of places, which took a minute to get used to! Cell phones were on the fringes that far back so I couldn't speak about them with any knowledge.
The people there were extremely welcoming and had a work ethic that I fear the US has lost. They took pride in their work and it showed. They were paid peanuts by comparison to an equivalent US based job. I was at a tire cord manufacturing facility. They made the polymer material for the tire cords.
Looking over my pics, all I can say is 12 years was a long time ago. You should have a great time.
The local landscape
Out my hotel window in Izmit
Me and the Mrs at one of the mosques
The same at the Cistern
My buddy Leo who ended up with an nice chess set and some pipes at the Bazaar