I will arrive in Athens at 2:30 AM. maybe 1/2 to 1 hr to clear customs. Need to take ferry to Syros at either 7:30 AM or 7:00 PM. Should I try to hang out and catch the morning ferry or try to find a hotel in athens and catch the evening ferry . If I go for the morning ferry where should I hang out?
Some omitted facts would help us advise better ... (1) when you arrive at 2:30 AM, is it after a 15=hour flight and 7-8 hours clock-time changes, so you are utterly exhausted, or are you coming 3 hours, from someplace in N. Europe or Spain? (2) is your visit to Greece a decent length?... at least 12 days or so, so you can use a day of "recovery" ... or is every hour precious? (BTW, there is no such thing as "clearing customs" there is essentially NO customs check, the only line is for Passport Control, and in wee hours, VRY fast).
IF your trip-time is limited I wouldn't waste a full day.... I'd hang out at airport until about 5 am -- there are a couple of cafes that have banquettes to loll against -- then catch the x96 KTEL express bus from in front of terminal... in wee hours goes about every 35 minutes, takes 65 mins or so... (there is a Suburban train to Pireaus also but it doesn't start running until after 6 am, takes 1 hr +) I'm guessing it's the Blue Star ferry departing at 7:30, it will usually open up by 7 or maybe a little earlier & you can go on board, get a snack & collapse.
Only reason to stay over in central ATH for 1 day is if you have never been there, have no room in your itinerary to visit Athens for 1-2 days at the end of your trip, and want to see the Acropolis.
thank you for the input, I really don't have time to "waste a day" and I've seen enough of Athens. We will be pretty tired but it looks like it would be better to recover on Syros than Athens, there are restaurants open at the airport it sounds like it would be a safe place to hang out and then get a cab or bus to the ferry terminal.