HYDRA - I agree that 3 nights there is 2 too many; it attracts a lot of "rickheads" because it's the only island I think that his book covers... but it really doesn't have ANY beaches -- at a time when beach weather is IDEAL.
AEGINA - "most of a day to get there" is definitely NOT true if you listened to TommyK; Aegina only 40 minutes by hydrofoil, only 60 by the infinitely more enjoyable "regular" ferries! Sit on open deck and enjoy amazing views of the Saronic bay and the variety of water craft ... giant liners, ferries, tiny sailboats, swift cruisers... plus seagulls, even a dolphin if you're lucky.
View this great pix album https://www.flickr.com/photos/36264706@N03/sets/72157621604646139/detail/ -- of a June day trip to Aegina It's even more fun to stay a day or two. Especially on weekdays, when Athenians are scarce,y ou feel a world away from Athens! On Marathonas beach, a short bus ride (or bicycle) from the port - here are simple accommodations right on the sands. http://www.aeginagreece.com/aegina/pages/accommodation/accommodation_index_marathonas.html -
AGISTRI - If you totally want to get away from Athens in just one hour -- try the tiny island of Agistri (Angistri) right next to Aegina. You can either take a hydrofoil direct, or take ferry to Aegina, and then a 10-minute "speedboat" ride to Agistri. Its an island of pine groves & beaches; you can rent bicycles; there almost no cars. This place - http://www.rosyslittlevillage.com - is an amazing hidden gem right on its own beach. Small, friendly, important when u are traveling solo.
DELPHI - I took one of those 1-day bus tours on my FIRST trip to Greece 17 years ago... and hated the whole experience. most of the time was on the bus, 3 hours up; 10 busses arrive at same time, and groups all went first to the ruins, stepping all over each other, and then to the Museum, which became jam-packed. THEN the tour guides yank you away before you've seen everything -- to go to a taverna for a mediocre meal you DONt' want and which YOU pay for (it's a kickback to the tour), and then to souvenir and rug shops (kickbacks, again) and a long bus ride, made longer by dropping people off at hotels. This was not an unusual circumstance; it's standard practice. Finally I wised up and in 2011, went back as a D-I-Y, with a friend (but it's just as good solo. You CAN do it as a 1-day D-I-Y, but so much more relaxed as an overnight. HERE'S HOW:
HERE'S HOW: Do "homework" (see list below). Taxi from Central Athens hotel to Liossion Bus Terminal (about €12-14). get a noonish bus to get there late afternoon. Check into Hotel (I loved PAN, with back balconies looking down mountain to sea; €35 in May). and walk down mountain road along parapet wall to Museum; in Ma it's open until 8 and EMPTY! Very good signage. Walk further down Athena "tholos" ruin. Sunset dinner at taverna with terrace view. Enter Ruins 8am, you have 3 hours before the bus throngs arrive, then bus back to Athens. If you want an expert Licensed guide, Georgia Hasioti http://www.delphi-guide.gr can meet you at the site ... very reasonable if you share cost with 2-3 others. NOTE: if you want to do it as a 1-day, take the 7:30 AM bus -- it can sell out so ask your hotel how to order it by phone or online. The last 2 busses back to Athens are 4 PM and 6:50. If u want to make sure your choice doesn't sell out, you can either buy a round-trip ticket OR, when reaching town of Delphi, go to the final stop in town & go into the souvenir shop/ticket shop & buy your return ticket before going to the ancient site.
MAPS - Printable maps of Museum, Sacred Precinct, Wider area http://www.planetware.com/map/delphi-map-gr-del.htm
GOOD INFO - http://en.wikipedia.org/wiki/Delphi • http://www.ancient-greece.org/archaeology/delphi-archaeology.html
• Dr J's Delphi - http://people.hsc.edu/drjclassics/sites/delphi/sacredway.shtm