Hi Michelle-nh,
My husband and I are going to Italy and Greece in May. I booked the Charming Oia Village through NCL just to get priority tender and cable car tickets back to the port. NCL told me that with this "tour" they will bus you to Oia for 1 1/2 hours of free time and then bus you back to Fira. We plan on getting our cable car tickets from the tour operator and staying in Oia and then catching a bus back to Fira later on in the day. The local buses run every 30 minutes from Oia to Fira. There's even a stop in between in Imerovigli. We may check out that town too. The bus fare is 1.60 eu pp.
In Athens, I think I will just taxi to Acropolis or catch the X80 bus. The bus is only 4 eu pp and the ride is about 20-30 minutes. You can buy the tickets to the Acropolis on the Helenic Heritage website. I think tour guides are available for hire there. I think this is doable on our own because we are in port from 7 am - 6 pm. With so many ports, these tours in every port are kinda expensive. Also, we are going to be in Italy for 12 days before our cruise so I'm looking to see what ports we can do on our own.
I have no clue about Corfu or Mykonos. I wanted to go to the Blue Caves in Paxos from Corfu, but with only 6 or so hours in port, that isn't possible. I'm still researching......
Marilyn