Mid February I took 6 days off and visited Istanbul. Unfortunately I wasted a whole day getting there and a whole day getting back, but this had nothing to do with delayed flights, time differences, bad traffic, and me forgetting to buy a visa before I landed.
Thus far, Istanbul has been the most active, vibrant, busy and colouful city I have visited. I had an awesome time there but it was not long enough. Perhaps I might visit it again a few years down the track.