In Oia you can check out the famous blue roof church then you can catch a local bus back to Fira. It is a 10km/6mile (each way) hike with incredible views. We did it together on our babymoon.
This is the oldest winery on the island. We almost booked the wedding here! It is beautiful! We recommend making a reservation to try to score a cliff view table, for a sunset. We recommend a dinner there or wine tasting with some local bites. We suggest pairing visit to this winery with a stop at Santo Wines, which is just "down the road."
A great spot for midday wine flight by a glass barrier overlooking the cliffs of caldera and a ship wreck in crystal clear waters. This winery is home to the best Assyrtiko (white wine from grapes grown on the island).
It's right outside of Fira town!
We cannot commit to naming our favorite, as all are super fun. They come in all colors (red, black, white, and all in between). They are quite pebbly as Santorini is a volcanic island, so we recommend aqua socks for those interested in extended walks on the beach (which we strongly recommend).