I stayed in
Marmaris for nearly 6 weeks from 11th Febuary-21st March.I was planning on being there for the summer but it didn't work out and had to unfortunatly come home
Regarding the weather we had some good days and some bad days.The good days you would always need a jacket and the bad days you would be in doors all day because it was raining,we even had a thunderstorm 1 day,i've got video's on my phone of that day!!
The bigger hotels like the A/I ones are usually open,a few places on the Marina are open,a lovely Chinese along the beach front was open when we was there and it has gorgeous food!
More and more places are staying open and you will always find something to do on a night time.Barstreet is open at weekends if you want a lively night.
I would deffinatly go again in the winter i loved it