trying to get some info on best areas to stay in Athens, Mykonos and Santorini. going from Sept 6th to the 18th.
If you haven't already done so you can search the travel advice forums for Athens, Mykonos and Santorini on www.tripadvisor.com All your questions will be answered and if you register (it's free) you can send private messages to anyone who might have the information you seek. In each forum look in the green strip at the top of the page for "Hotels" and "Things to Do". This will give you a good idea of the best areas available depending on your personal requirements.
In Athens, I'd suggest the area around the Acropolis or Monastiraki Square. The southern edge of the Acropolis, near the Acropolis Museum, is quieter than further north but equally convenient. We stayed at the Herodion Hotel which we liked, but there are many others in that neighborhood.
In Athens stay in the tourist zone that branches out from the Acropolis to the north. In Santorini, stay in Oia on the rim of the caldera. Have never been to Mykonos so can't help you there (but the RS Greece guide can).