santorini and mykonos

Very near to Atlantida is the Sigalas Winery. It's practically across the road, and down a driveway that runs next to the Santorini Mou Taverna. For something more elaborate the Santo Winery in Megalochori is probably your best option, but there is also an island winery tour offered. If Atlantida doesn't have the details you can go to the travel office in Oia near the beginning of the pedestrian-only walkway, which begins across the street from the Laokasti Restaurant and Villas. They may also have information about any cooking classes available. These seem to come and go quickly.

You can hike the trail between Oia and Fira that begins just past the desalination plant, which is very close to Atlantida.

Have lunch down below Oia at one of the fish tavernas on the wharf in Amoudi Bay. Be advised that fresh fish is priced by the gram so it can get very expensive. Be sure to ask the price before ordering.

On Mykonos, you can take buses to different beaches and destinations that are quieter than the main town. May is not high season yet, but I would expect some buses to run; confirm schedules locally, preferably with a live person, or something that has this year's date on it.