Well, in that case, go to Hydra which is popular and very picturesque, the shops are open and you can get there in 1.5 hrs. with the flying dolphin and then there is Spetses, where I happen to live. 2hrs., places are all open at the week ends and some stay open for the week like some restaurants in town. Beautiful walks and hiking etc. walk to the old harbour and see the sea there, very nice. have fun.

The point with Aegina is that it's only 30 minutes away via flying dolphin, or 1 hr by normal ferry, and there are hourly departures from 06.00 am until 09.00pm. The chance of having your ferry canx due to a weather ban is not as tragic, in that you will simply catch the next available ferry, when the ban is lifted. With islands further away, and departures not as frequent, in the event of a weather ban, you run a higher risk of getting stranded on the island overnight or more.

that is true about the ferry boats going more often and maybe the weather is not good on that day for the boat to go or come back. That is not very often, but it does depend on the weather at that time. Seeing you have only one day try something closer. Like #6 said, try Sounion, that is nice there and you see the coast also a little and the view is great.