I've done two island-hopping tours of the Cyclades now, covering all the islands you mention. My advice would be to cut down Santorini and Mykonos to 2 nights each and use the extra nights on Naxos or Paros.
Despite Santorini and Mykonos being the most famous islands, neither are that amazing (in my opinion): Santorini only has the (admittedly) stunning caldera view and the sunset at Oia, both of which could be done in a day. Mykonos is a pretty island but the amount of tourism has ruined it really. Both islands are very expensive in terms of accommodation and food/drink, and extremely crowded most of the time.
With the money you'd save dropping the third day on each island, you could splash out on Naxos which is a beautiful island. On Paros you can also visit Antiparos (a 10-minute boat ride from Pounta).
I think that's quite a lot of islands in a short time.
Each time you move island you waste quite a lot of time travelling
Two nights on an island means only one full day, so IMO it would be better to stick with at least three nights each. I agree you have two many islands, though, so it would be best to eliminate one and add the nights to the others.
Which island to drop? Go to Mykonos if you want high end hotels and restaurants and the the best nightlife, but apart from that the other islands have more to offer. If you want to keep Mykonos in your itinerary, then choose between Paros and Naxos, which have equally good sunsets to Santorini. You can enjoy a beautiful sunset without the crowds at Sunset Beach on Antiparos.
I read this thread earlier before Heimdall had replied and I was going to suggest something similar. I agree you have too many islands and it would be better to stay longer in once place, e.g. have 6 nights on Naxos to relax a bit. From there you could do a day trip to Paros (using ferries) and even include Antiparos. As an alternative you could take an excursion boat to Iraklia and Ano Koufonissi.
Will, Koufonissia is not another name for Koufonissi. Koufonissi by itself is a shortened form of Ano Koufonissi. Koufonissia is an archipelago of Ano Koufonissi, Kato Koufonissi and Keros, but only Ano Koufonissi really has a population and is the only one you can get a ferry to.
@GreecemadUK - ah ok, thanks for the correction! I'm sure I had seen them used interchangably before, but I may have misunderstood the context.
I think you have a great plan, at least 2 full days on each. And stick to your 3 nights for Santorini as it's a beautiful island. Yes it's crowded and there is a reason for that. You could rent a car for a day and tour the island as there are some nice tavernas on the sea and a few nice villages.
Like also mentioned by Heimdall:
Take into consideration that staying anywhere for 2 nights will only equal one full day.
It's still a lot to fit in with the time you've got. You've not mentioned your means of island hopping. Bear in mind each hop will lose you best part of half a day by the time you've checked out, travelled to the port, got on a ferry, travelled to your new accomodation, checked back in etc...
I understand the temptation to fit in as much as possible when travelling a long distance to get to Greece.
I always have a very busy itinerary when we do USA trips as I know it's unlikely that I will be returning to the same region again.
However, with island hopping in Greece I do think it's worth mentioning that "less really is more"!
Athens plus 2 other islands is more than enough.
I think it is a great plan! And 3 nights on each Island...perfect! And since I am traveling with you, even better!! When did you join Trip Advisor?