Tours from Seville while on a cruise

I presume you mean the official, long-established, horse show in Jerez, and I presume that you mean "ship excursions", which will force the ship to wait for them if they are late returning from whatever the tour is. If anyone in your group rides, or likes horses, I certainly suggest the unusual performance. If I wanted to see the Alcazar, I would do that on my own, assuming there is an easy way to get into town from the port.

Alcazar

I didn't see the Andalusian horse show in Seville, but I did see it in Córdoba, and I honestly didn't particularly like it.

The Alcazar was one of the highlights of my recent two-month visit to Spain.

Does the tour originate in Sevilla, or at the cruise port?
The most famous horse show is in Jerez, which is about an hour closer to the port than Sevilla.

I would hire your own driver rather than going on a ship's excursion.

There is almost no chance of you "missing the boat," since if, in the remote instance that the car breaks down, the driver will get another car to finish out your trip and get you to your destination.

You really ought to do some reading about the two choices before you decide.

How about if a bus hits a bridge abutment and blocks the road? How about if the ship has to change piers and you have no way to learn that? How about if rush hour traffic makes you two hours late?

I have had all of those experiences, sap that I am, to have paid through the nose for the lousy Ship tour ... ...

All I can offer is my own opinion based on many visits to the provinces of Seville and Cadiz I would not book a ship tour but would, instead, hire a driver to take me to whichever site I was interested in while my ship was in port. Imagining that the dock is in Cadiz, another option would be to explore that lovely city, with possible ferry to El Puerto de Santa Maria, or even a visit to Sanlucar. But those latter two may not be included in the RS guide.

I have been cruising for over five decades, and I see no need to debate here the decision to take a ship excursion or not. That does not respond to the OP appropriately.

First, stopping in Sevilla for just one day would be quite difficult, as there is absolutely so much to see and do!

We travel to Spain for all the great historic places, so I could not possibly say I had been to the city of Sevilla without visiting some of the most important sites, and of course, the Alcázar is extremely high on the list. So, if you like history, and architecture, and learning about Spain, then the Alcázar would be the first choice.

However, if you have limited mobility, you tire easily by walking, or you are focused more on the cruise just for amusement, they why not go to the horse show? IMO the Andalusian horses are some of the most beautiful in the world, and certainly it is quite entertaining and thrilling to watch them in action!

By the way, I am cruising to Iceland next month, and I have been there several times in the past, so I just booked a ship excursion to go horseback riding on the famous Icelandic ponies. Hopefully we will cross some lava fields!

No, I would not book that tour independently unless I was staying in Iceland a few days, just because sometimes it is easier to have everything prearranged when one is on a tight timeline.

Bon voyage!