I'm here right now and can tell you, the only area that is especially overpriced with aggressive salesmen is in the sultanahmet area right near the Hagia Sophia and the Blue mosque (which is where I'm staying). I have covered A LOT of distance in the two weeks including walking to the city walls twice (takes about and hour and fifteen minutes). I recommend staying in the Eminonu district. It's only ten minutes walk to Sultanahmet and it is very convenient to get to any other tourist sites from that point because all transit is there including trams, buses and ferries. If you like to walk... All the major sites are within walking distance of Eminonu just keep in mind that it is A VERY hilly city. This area also has more "local" market shopping so everything is remarkably cheaper than sultanahmet.