Since the volcano has no main crater, which would make a tour more spectacular, we have decided to take a ride just around Nea Kameni.
However, most of the trips were offered only in package, where you visit the hot springs being not hot at all, in Palea Kameni and afterwards also Thirasia with a lot of low quality taverns.
The cheapest tour, I have found, would have cost 180 €, but I got also an offer for a 135 € per person "you do not get what you pay for" tour.
Unique Suggestions: We did not take any volcano tour!!!
Fun Alternatives: We took a ride by a tiny fishing boat from Kamari beach to the lighthouse and back.
The views were simply amazing, looking to the beaches, the caldera and the neighbouring island on the Aegean Sea for a fraction of the cost of the volcano tour.
While in Santorini, we noticed that a lot of huge cruise ships stop there for half day.
Fira is located on the top of the caldera, while the port is at obviously sea level. It is possible to reach the city by climbing a long mule track (either on foot or with a mule) or by cableway. In both cases, since a cruise ship hosts a large number of tourists, it takes ages to reach Fira and we saw a lot of people (above all those with children) staying in the port, which is nothing worth seeing. Moreover, Fira is a very small city which is litterally invaded and that cannot be appreciated in all its splendour...
Unique Suggestions: I think it is preferable to enjoy the island from the cruise ship, at least you can get an overall idea of how magic this spot is.
Fun Alternatives: If you want to visit more than one island in the Cycaldes, you can take ferries to move from one island to the other. Connections are affordable and very frequent.