3rd island?
 

I originally posted about visiting Hydra, Santorini, and Mykonos. After your recommendations I think we will skip Hydra and add a different 3rd island. Recommendations? Crete? Paros? We. Are looking for a good mix of relaxing, hiking, and history.

We are going towards the end of may.

Either Naxos or Paros would fit in nicely in your itinerary.

Paros is on the same highspeed ferry route as Santorini and Mykonos, so for me that's the logical choice. But are you planning to spend any time in Athens? Don't you have to be back in Athens for your flight home? If you want to relax I think you really only have enough time for 2 islands unless you'd be satisfied just to barely scratch the surface.

In your other post you wrote you will be flying into Athens, and I'm assuming you will be flying home from there as well. Unless you book connecting flights it's almost impossible to avoid a night in Athens at the end of the trip. If you've never been to Athens before, it would be a shame to pass up the opportunity to spend at least a day in that historic city. It would also give you a buffer in case weather or industrial action delays your return from the islands.

It is unclear in your posts whether the 9 days of your trip includes days of arrival and departure — if so, that would leave only 7 days for "relaxing, hiking, and history." Visiting three islands would use up another two days in travel, transfers, and checking in/out of hotels, leaving only five full days for relaxing and sightseeing.

My advice would be: stick with just Santorini and Mykonos, and allocate at least one night for Athens at the end of the trip. :-)

Sorry I should have clarified. Spending two nights in Athens before we head out to the islands. Wouldn't miss the history there!

Conventional wisdom recommends saving Athens for the end of your trip so you don't have to scramble back to the mainland at the last minute for your flight home. Nothing will ruin your vacation faster than missing that flight home because of a delay or cancellation out on an island.

I agree with botherleelove. Get a connecting flight directly to Santorini or Mykonos upon arrival in Athens if you can. The flight to the islands is actually quicker than the transit to central Athens, and saves you one check-in/check-out cycle. The vast majority of trips to Greece go without a hitch, but if there were a strike or severe weather when it is time to return home, I would rather be in Athens than on the islands, so saving Athens for last is a good idea on both counts.

Nine days just for the islands certainly helps, but consider this: you will lose time travelling from the islands and back, and more time for each island transfer. If you visit three islands you really have only two days on each. :-)