We spent two days in Athens before our cruise, visiting the Acropolis, New Acropolis Museum, and archeological museum, so we chose the Delphi excursion on the first day of cruise to see a little of the surrounding area. In Santorini we did the Best Of Santorini excursion. It was ok but Oia was very crowded with four ships in port that day. The included lunch was good. Neither of us remembers anything else from that day other than the cable car fiasco so it certainly wasn’t all that memorable for the extra cost!
If you have extra time after the Acropolis tour, the shuttle pickup location is very close to the pedestrian friendly Plaka shopping area. I thought prices in Greece were very reasonable, for food and souvenirs.
In hindsight, we preferred the included walking tours where available to the ones where we drove on a bus for an hour each way to see something. It seemed we saw a lot of roadside scenery but didn’t really get a good feel for the area. My favorite excursion was Ancient Olympia. All of our guides were great but the one on that excursion was very knowledgeable and personable.