The food is fantastic in Vinces, but I have not had a bad meal in Icmeler, there are loads of fantastic places to eat. I dont eat in Vinces every night as I like the variety of different places, you will be spoiled for choice.
Marmaris is only about 10 minutes bus ride away on the dolmus. These little orange and white mini buses run every few minutes back and fore from Icmeler to Marmaris - cheap too. Just jump on one of these, they only cost about 3 lira.
ICR also do some very good trips, I can recommend the all inclusive boat trip, jeep safari and the Turkish baths, excellent value.
Just one word of warning, its extremely hot in Turkey now and will be when you go, make sure you take plenty of high factor cream with you as its quite expensive in Turkey for sun cream and I dont think its the genuine stuff either.