I will be traveling to Greece the first week of October. Want to visit one island. Only have one day to play with a possible overnight before back to Athens. Also, is Crete worth the time/journey? Recommendations? Thanks.
Crete is a large, varied island. I certainly wouldn't go there for just one night, if that's what you're asking.
I have visited all four. Either Santorini for stunning quiet beauty but quite expensive lodging usually with minimums during summer or Mykonos windmills interesting whitewashed paths for lively walks ,charming and entertaining nightlife. Crete only for palace of knossos, so leave for another time.
Why not consider Nafplio... looks like an island, feels like one (at the tip of a peninsula, surrounded by water), gorgeous "old Town" Venetian houses, stunning sunset from seafront cafes, full of history, chic shops, the town square is Paved in Marble. Stay One night and get back easily ... y ou can go via intercity KTEL bus in 2.5 hours, going along the Saronic Bay, across Corinth Canal, then thru beautiful orange groves, and olive groves. In the fall, it's lively, with Athenians enjoying a quick "getaway" ... lovely restaurants w. outdoor tables, it's all good. You can even get a quick Swim at the town beach!! Here's the best (and NONcommercial) website, done by a Scandinavian expat == http://www.visitnafplio.com -- click on all links including "Really useful info" (directions to get there, were to stay, dine, shop). Here are great pix -- https://www.flickr.com/photos/stanbr54/sets/72157632094108982/ by my fellow Nafplio fan-guy, "Stanbr." and some videos as well! https://vimeo.com/visitnafplio/videos
It's quick, it's beautiful, AND economical -- 1 way bus fare is €13 ... and a taxi to the KTEL bus station is about €11=12 1st bus is 8, then 9:30 and hourly on half hour. GO!
Thanks to all who replied!