I took the RS Greece tour 2 years ago since then I've had a nagging itch to go back for more. My current nebulous idea is to visit 2 or 3 islands, 4 or 5 nights each, though one could be 3 nights and tack on 3-4 nights in Athens. I would fly into Athens (flights to the islands early in the month look to be sold out) back from one of the islands (Heraklion, Santorini, maybe Rhodes). My dates are flexible, any time from early to late October. I've looked at historical weather for Heraklion and Athens and it appears that it's mostly sunny and pleasantly warm, but not hot (I hate hot weather).
I do not want to rent a car and I don't want to change locations, once I'm on an island unless it would make sense to spend at least 3 nights in each location. So I want islands where I can sleep in one place and have enough to enjoy for 3-4 days, which could include day trips by bus or ferry. I don't want a lot of beach time, though I'm sure I'd enjoy a couple of lazy afternoons in a beach chair reading a book and sipping a cold drink. I like exploring scenic villages, easy hikes, history, archaeology.
I welcome your suggestions.