This was our second cruise on the Serenity and I would rate it very highly again, with a couple of areas for improvement.
The food is consistently wonderful. Last October we thought that Prego was good, but not better than the dining room. This cruise we felt that the food was improved, with more selections that were different than what was served in the Main Dining Room. Silk Road was delicious again.
The Main Dining Room and the Buffet were both impressive, as was room service. The second-to-last evening's Dover Sole meal was truly spectacular.
AS noted above, cabin is small but very cozy and well-designed. Our cabin attendant kept it spotless. Plenty of room for two on a one-week cruise. I wouldn't try to have a third person in the room, though. Love the veranda. Bed very comfortable. A/C worked very well, unlike many hotels.
We did not take excursions here, but simply walked around the city a bit and took a few Lyfts to some more far-flung locales. Great port stop. San Fran never disappoints.
Again, we made our own excursion to the Zoo, since Crystal did not offer one (!). We ordered tickets online in advance and called a Lyft to get there. It was within a short distance of the pier. It was well worth seeing.