We are flying into Athens next May and will fly home a month later out of Santorini. We would like to visit Milos, Naxos, Paros and possibly Sifnos or Folegandros or Ios. Looking for suggestions on routing, planning around 10 days in Naxos, 5 in Paros, 5 in Milos, 2 in Santorini. Gives us around 7 more nights. Could spend time in the Peloponnesus prior or? Would appreciate suggestions. Would also love to fly to Chios.
At this point, I will just pass on some general thoughts. For Greece, it seems the fewer destinations planned the better. Any time you change locales, it is a killer of time for the day, basically a lost day. If you think you might be adding too much, then you are.
Do some trials on Ferry websites. Sometimes, you just can't get from one island to another, even close islands, without routing back to the mainland or way out of the way. Also if there is a ferry, it may only be a few times a week, meaning you might be restricted to only a couple nights on an island, or need to spend most of a week to make the route work well. Also timing of ferries can be an issue, changing routes (arriving on an island with the intent of not staying, but getting another ferry) is subject to schedule disruptions, or just sometimes require an overnight to work.
Off the top of my head, Athens-Paros-Naxos-Santorini is easy; adding in Ios probably works; Sifnos and Folegandros are the ones that might take some route planning to avoid backtracking.
The Peloponnese is worth a look, many like Nafplio, easy to get to, access to Mycenae and Epidaurus ancient sites.
Not too far from Nafplio in the eastern Peloponnese, if you’re not making it all the way to the Archaea Olympia temple and Olympic Games site way west, is Nemea, which features its own stadium, along with a unique tunnel leading to it, complete with scratched-in-stone graffiti from long-ago winners. It has a wonderful, small museum and some ruins, too, with a partially reconstructed set of columns. Worth a visit, and offers so much with almost no other visitors, it seems.