Nafplio
Since it's not an Island, Nafplio doesn't get as much screen time as other Greek destinations. But don't let that fool you. This was one of my favorite spots. It's small, making it walkable. It has some outdoor restaurants along the sea and offers some history, shopping and a great beach. Avoid the crowds and sneak off to Nafplio.
Hike Palamidi Fortress- The sign says its 999 steps. It gets hot in the sun, but the view just keep getting better and better.
Walk Arvanitia Promenade to Arvanitia beach- This was one of the top three things I did in Greece. It takes about 20 minutes and ends at the white stone and pebble beach. Treat yourself to a cold beer and hop in the water for a swim.