How Much Time Do You Need? in The Sea of Marmara and the North Aegean

The Sea of Marmara area can be a quick one- or two-day trip from Istanbul: you could do just a day in Iznik (make sure you leave Istanbul early), but you'll want to spend an overnight, at least, in Bursa. If you're just planning a day trip or an overnight to the area from Istanbul, the ferry from Istanbul's Yenikapi terminal to Yalova takes about an hour, and then you can catch a bus to Iznik or Bursa.

If you have two or three days in the region, visit Gallipoli and Troy, maybe adding a day in the Mt. Ida region. If you have five or six days, you can pretty much see everything in the area, continuing on to Behramkale (Assos) and Ayvalik, with a visit to Cunda, Ayvalik's main island, and the ruins of Pergamum. Be warned, though: Mt. Ida is lovely and has wonderful hiking. Once you get there, you might want to stay longer.