I haven't been to Naxos so can't speak of that but we really enjoyed the 3 nights we stayed in Nafplion in April.
It was a very relaxing few days in a very pretty area!

HiSanda!

The NAFPLIO OPTION - Getting to Nafplion from an island is always a long process by public transport ... and I should know, I've tried it at least 3 times. Problem is, you can't get a bus direct from the airport OR from Piraeus. From the airport you have to take the X93 Bus to Kifissou KTEL bus station (about 70 minutes). Then catch a KTEL bus that leaves hourly on the half-hour, takes 2.5 hours. If your timing is lucky, you won't have to cool your heels in the gloomy KTEl station. The easiest and hassle-free way would be to rent a car at the airport (u can get a small car for 40 per day or so)... and zoom to Nafplio on modern divided highway.. Then u could use the car while there, to easily see nearby ruins like Epidaurus. Then u don't have to return to Athens, just drive on to Delphi of an afternoon, stay o'night, and you'd be able to enjoy Delphi in the early morning sun, 8 am on, long before the bus-tour crowds arrive.... and the savings you would realize by self-drive vs. those tiring bus tours Athens-Delphi would pay for your car rental. (Of course this means you'd need to do some homework for a D-I-Y tour of Delphi, but internet sources are Excellent & you have time to study up).

The NAXOS OPTION, however, has great appeal as well!! [You DO realize u have chosen my 2 favorite places?!?!]. Naxos is SO different from Santorin! For one thing, golden-sand beaches, 15 miles in a row. For another, No Crowds (because no big planes, no cruise ships). If you stay at the Ag. Giorgios beach adjacent to Naxos Town, you can even swim! Because t that beach is shallow & water warms up more quickly. Another contrast; Naxos is green & fertile & full of wildflowers in May ... great for hikes, or a car/scooter tour.

Again, it helps to know the transportation back to Athens. Blue Star ferries are the Gold Standard -- but alas, the 9:45 am takes until 3 pm, eats up the middle of the day. My tip: take the Blue Star "sunset ferry" sailing... leaves about 6:15, arrives a little before midnight. Sit on deck for sunset, get a bite to eat in one of the cafes, then go inside to snooze or read. That way you get a full final day. NOTE: you'd have to check out of your hotel room by noon, but if u ask your hotelier, you can have use of a bathroom after a few hrs on the beach, for a quick shower & change.

SO ... 2 great solutions. How to decide? It's a win-win situation. They BOTH offer history, landscapes, AND beaches that are swimmable in mid-May (Nafplio has a town beach AND nearby Tolo). As I always do when advising about these 2 places, I end by giving you links to two wonderful sllide-shows by Fodorite Stanbr, that show you the beauties of both:
NAXOS -- http://travel.webshots.com/slideshow/552001505EYxVYT
NAFPLIO -- http://travel.webshots.com/slideshow/551991579dJbWvh

thanks, Jan! Those pics are gorgeous. I've kicked myself several times since booking this trip that we didn't plan more time in Greece but . . . as it is .. that first week of May it looks like there's only one ferry from Santorini to Naxos - 3:30pm. Is that possible? I'm kind of bummed because that would mean we'd only have one full day on Naxos because the next day (Sunday, May 8th) we'd fly back to Athens (6pm flight) We wanted two days at the end to see the sites in Athens. Is it worth traveling to Naxos for such a short time or should we just add another day to Santorini (now we have 2 full days and two partial days) sigh - not enough time to do all we want

I do not quite understand sanda. You say you have "a couple of weeks in GReece" . To me, that means 14 days. And then yo mention 2 full days & 2 partial days in Santorini and 2 days for Athens ... that still leaves at LEAST 8 days. What am I missing here??

About ferries -- in early May there aren't as many ferries as you might wish.

Please clarify how 3+ days in Santorini and 2 in Athens uses up most of 2 weeks. Then we can advise.

ahhh . . yes, that would seem confusing! My "two weeks" was a ball park - actually it's 11 days including to and from. I realize now I should have said a week and a half . ..

Day 1 flight to Athens
Day 2 Arrival Day - stay in Athens (we arrive 9am and don't want to wait for the 4pm flight which appears to be the earliest we could make and don't want to spend all that time on a ferry when we could be seeing sights in Athens

Day 3 10am flight to Santorini
Day 4 Santorini
Day 5 Santorini
Day 6 3:30 Ferry to Naxos
Day 7 Naxos
Day 8 Naxos with 6pm flight to Athens
Day 9 Athens (this is a Mon so there are no flights from Naxos if we wanted to extend a day)
Day 10 Athens
Day 11 head home

Hi sanda24,
That sounds like a good trip plan!

So, it is now clear -- supposing you reach Central Athen & check in to your hotel by about 12 noon -- instead of 14 days, you have 8.5 days. Big difference ... but I am sure u will make every moment count! Enjoy... it's a great time of year (tho be prepared for fairly chilly swims).