We will be in Istanbul for 5 days in August at the end of our month long trip to Prague,Rome, Santorini,and Mykonos.
Are there any day trips we can take?
Is it possible to see Ephesus in a day from Istanbul? What did you do in or around Istanbul that you recommend.
Thank you

I just spent a week in istanbul and could have stayed longer. Its an amazing city with loads to do so think about trying to rush it with combining it wth something else. We spent a day at the Blue Mosque, Aga Sophia, the carpet museum, the Basilica Cistern and the Spice Bazaar with a lunch break at the not to be missed Four Seasons in between. Then we spent a day at Topkapi Palace including the harem followed by a cruise from Eminonu. I spent a day at Ortakoy on Sunday wandering in the flea market and having a lesiurely dinner by the water and did another 1 hour cruise. Half a day at the Grand Bazaar. Half a day at nisantasi - definitely sit at the cafes and people watch, an experience combined with the military museum including the afternoon band performance. Half a day at Iftiklal cadessi. Half a day at the Dolmabache Palace. Is SO Much to do! Some of the best restaurants I've experienced - google Mikla, 360 istanbul, Hamdi Loktansi, Hunkar. At the end of so much traveling I'd just spend the entire time in istanbul and soak up the wonderful city!

No day trips from Istanbul, please - this is one of the most interesting cities in the world, and five days are kind of a minimum stay. For a thorough visit of this marvellous city, you'll need four to five WEEKS, so there's plenty to do for five days.
Check this website: http://www.istanbulguide.net; it's wonderful and terrible at once, the programmation is terrible, extremely confusing, you'll need half a day until you'll understand in some degree where to find what, but the content is admirable, they're listing, and explaining very well, really each and every monument, most of them with pictures included, it's the best source on Istanbul, better than every guidebook. (Available in French only, though.)

Altough the other posters are right with the time to spend in Istanbul, answering your question if you wish to visit Ephesus anyway:
Yes you can do it in a day. Take realy plane to Izmir, have someone to pick you up and guide through the sites and take the late evening plane back.
Happy travelling,
Murat

I agree with Hobbes and Franco....a month would not be too long to spend in Istanbul. Hobbes gives you some good eating recommendations.