On a cruise that stops at Santorini. The ship docks at 1630 (4:30pm) and departs at 2130 (9:30pm). Given this short time frame and the fact sunset is around 1900 (7:00pm), looking for way to make to the most of our time on the island. Have considered hiring guides for walking tours as well as private car tours. Thoughts or suggestions?
The towns are too small to merit walking tours, maybe a hiking tour?
Take a bus to Oia, see views, town. Go to a winery. Go down to Amoudi Harbor. I doubt you have enough time to visit the outstanding Akrotiri. What cruise ship is this? They are giving you too little time and at an odd time of day.
Usually there are long lines for the funicular that takes cruise passengers back down to their tender dock; this cuts into your time.
Hiring a driver may be best to maximize your very short visit.
That is not a lot of time. Hire a round trip driver to take you to Fira, the main town. Walk around, sight see, visit the shops, have a drink and some meze in a lovely spot with a caldera overlook, and then catch your ride back to the ship. Adding anything more to your visit will lead to stress, imho.
Are you sure these times are accurate? If so, you have very little time on the island, especially since you usually have to take a tender from your ship to the dock. I would call the cruise company to confirm the times. You may find that taking their excursion is the best option.
For independent travelers, the tenders arrive at a dock far below the Old Town in Fira. At this dock you can take a boat tour to Oia (there are plenty of tour companies at the dock looking for clients), or take the cable car (or donkeys) to the town at the top of the cliffs. If your time is this short, I would probably just stay in Fira and walk around the town. Be prepared for a long wait to get on the cable car to go back down to the dock, especially if there is more than one cruise ship in the harbor.
Such short time for Santorini..... considering that you must be on board an hour prior to cruise ship leaving (8:30) you have very limited amount of time. Visit Oia and enjoy a nice dinner with a view, go down to Amoudi Bay, it truly is remarkable. Walk around the shops. You really don't have time for anything else, I believe cruise ships are tender in Santorini so that will take a bit of time to get off. Arrange a private driver, that will be the best way to see Santorini...