Be sure to take a hotel in the old-town area (Sultanahmed) for your first visit in Istanbul. That will allow you a most convenient sightseeing tour as recommended above. All the sights are in walking distance from each other. A hotel in the old quarter should be the cheaper and more atmospheric option too.
If you want to explore the nightlife in the Taksim Area, go there by taxi.
If the weather is fine, a cruise to the Princess Islands is indeed highly recommended. Weather in March will most likely be sunny and warm (temperature ~20C, no rain) but there can be indeed some chilly winter reminders if the wind is coming from the northeast. Be prepared for both and youŽll fine.
Originally Posted by
bcmatt
I went to the Princes' Islands last year in early April. The weather was indeed changeable, pretty warm and sunny in morning (we risked wearing shorts) and chilly and windy in the late afternoon (at which point we regretted wearing shorts!!). Best to be prepared for anything!
Please donŽt wear shorts in Istanbul. Although considered Europe and with usually very open minded and nice people, Turkey is an islamic country too. Nobody will hurt you if you do, but wearing underwear in public will be for sure the best way to make a complete fool out of yourself.