Edit: As pointed out below, Taormina won't be a good option from Palermo, so disregard my response. But I will leave it up for anyone visiting from the Messina port in the future.
We did the tour to Taormina and the Greek Theater. The tour guide wasn't great. If I did it again, I might just arrange for transportation and tour on my own. We ended up ditching the tour guide by the time we got to the theater, which is at the top of the town and exploring on our own anyway.
Taormina was one of the coolest towns I have been to. It sits at the top of cliffs that offer breathtaking views in many locations from the town. The town's main street is medieval style, narrow, pedestrian only, and lined with fun shops and great food, where you I had the best cannoli I have ever had. The town itself has a roman, Greek, and Islamic history, making for a very interesting mix. Large flowering trees grow all over town. There are narrow allies lined with flowers, inviting you to explore. Balconies line the tops of the main street. It's extremely picturesque, like walking into something created by Disney because it seems so perfect, but it's the real deal. There is a very cool garden near by too, which isn't on the tour. It's free to enter and walk about - it was created by a woman long ago for the animals that she loved, with lots of interesting buildings and plants. The Greek theater is cool too and sits atop more cliffs with great views of the sea. In the distances, there are mountains that tower even higher, adding to the ambiance. You can also see Mount Etna in the distance and many points in the town, often spewing smoke. The place is just surreal and beautiful, and easy to explore on your own. The drive there is beautiful too, even though it is 45 minutes. Winding up the cliffs to it, in a giant bus, is an adventure in itself.
If you watch White Lotus, Season 2, you will see a lot of the town and even the theater.
It just make for the perfect day. Sicily it like a different country than Italy in many ways. One day we plan to go and stay an entire week there, since each region with Sicily varies greatly too.
I also went in, almost randomly picking the tour, with no expectations, so that may have added to the experience. But my wife and I talk about how much we loved it often.