morens wrote:We are considering to stay in Apollonia in September.
Then you must be planning to visit Sifnos, lol!
Seriously, there is no Apollonia in Milos. This is a common error people make. The village you are referring to on the northestern part of Milos is called "Pollonia" (neutral gender, plural) as opposed to "Apollonia" (feminine gender, singular) in Sifnos.
In any case, September is perhaps the best month to visit Milos. Prices are low, while the weather is excellent and the sea is still warm. Pollonia in particular is a fantastic resort, built around a beautiful bay with a tree-lined beach, excellent lodging and good restaurants. You may even visit nearby Kimolos for a day, via a ferry that takes 10 minutes to cross to that neighboring island from Pollonia.
If I were you, however, I'd avoid dining on the coast of Pollonia. This is hearsay, but with the notable exception of "Araxovoli", the restaurants right on the coast are notorious for serving food that is neither fresh nor a good value for your money. All other restaurants in Pollonia, however, (4-5 of them) are very good. My favorite one is called "Filetaki". Tell Frangiscos or Margarita that Andreas Belivanakis sent you.
As for places to stay, I can personally vouch for Stavros Rooms, Efi Studios, Kalimera Rooms, Villa Maryelen, Kapetan Tasos and Kostantakis Studios. Andreas Rooms (no relation) is also supposed to be very good, but it is unlikely you'll find any vacancy unless you book several months in advance.