Hi
Well I like Turkey at any time of the year and am going next week for a break. However March is a little early for the holiday season so not everywhere will be open and things like boat trips are unlikely to be up and running. Weather wise you should be lucky and get some sunshine but also you could get rain. You'll probably find daytimes warm enough but evenings will be chilly. I find the sea too cold in March although my husband braves it.
What you will get are the most beautiful spring flowers and fabulous views. This is a good time to get out and about exploring so take your walking boots. The roads will be quiet so it's a good time to hire a car and if you don't fancy that haggle with a taxi driver to take you out for a day or make use of the public transport. Have a great time.

We were in Icmeler last March - week after Easter. Many of the restaurants were closed and they were preparing the beach for the summer influx.
We only had one day with some rain, otherwise it was hot enough for sunbathing, but the evening were very cold. You had to wrap up well if you wanted to sit out at night.
We enjoyed our holiday, but we went AI.
Hope this helps.

Marn.

we have been the last 2 years in march and are going again this march. we found that the weather is around 18-22 approx between 11am-3pm, we had a few cloudy days, but better than weather here and most of the old town in marmaris is open , and i personally prefer marmaris out of season

We went at the end of March last year and apart from a near monsoon downpour on the first day it was great after that, sunbathed everyday although as said previously its a fleece job at night, there were some restraunts open in Icelemer and you will find the Turkish people will spend more time chatting we even went off at two in the morning to play football with the guys from Dream Boys Restraunt Icmeler( 40 year old trojan representing England totally embarrassing his 16 year old son and scored late on when son had packed in with exhaustion )

Boat trips were running as we went from Marmaris, but yes sea colder although not beyond the limits of a swim and certainly warmer than the English sea in summer!!