Just back from a week in Kos Town (23 Sept - 30 Sept 2004)and highlight was day trip to Turkey. Booked our flying dolphin trip at one of the travel shops - 15 euros each and then another 5 euros had to be paid at the port before boarding. Have to say no one really explained what happened at the port, first you had to queue with your ticket and have a sticker put on your passport and get a boarding pass, then another queue to get into the area where you boarded the boat. Crossing was very quick, about 25 mins. On arrival in Bodrum you have to hand your passport over and receive a card which you need to collect it on your way back.
Found the shops cheaper in Bodrum for a lot of the usual stuff - handbags, shoes, jewellery. Plus cigs were only 15 euros for 200 as opposed to 27 in Kos. All the shops and restaurants accepted euros so no need to change money there. An excellent day out which I would thoroughly recommend.
Just returned from a week in Kos Town (23 Sept - 30 Sept 2004) and the weather was scorching - just like the height of summer. No need for a cardigan or jacket at night.
Resort was obv quieter than in the height of the season and no problems getting a sun bed on the beach.
All in all an excellent holiday I would definately return in September. I've been to Crete at roughly the same time of year and weather was not as good, much more mixed.