Sounds like a great trip you've got planned. I am guessing you haven't visited Istanbul before?
If it's your first time I would pass on the Gallipoli and Troy tours and spend your time in Istanbul.
Some of the things I have done on my visits there:
- Cruise up the Bosphorus, stopping off at the Rumeli Fortress and the trendy towns of Bebek and Emirgan.
- The underground Basilica Cistern next to Aya Sophia.
- Stroll down İstiklal Caddesi and its antique backstreets and fish market, through to the cobbled streets of Galata.
- The Istanbul Archaeology Museum is fantastic and contains the sarcophagus of Alexander the Great.
- Take a ferry over to Kadikoy on the Asian side of the city and its fantastic markets.
- Visit the Dolmabahçe Palace, often overlooked with the Mosques the main tourist attractions.
- Have a turkish bath, Kılıç Ali Paşa Hamamı being one of my favourites.
Last but not least, eat!
My partner wrote a blog entry on eating in Istanbul if you are in to that sort of thing with some of the places we make a trip to on every visit.
http://www.thecutlerychronicles.com/...-istanbul.html