I may be biased, but the terminal in San Diego was an absolute breeze..and we arrived just before noon and were in our cabin at 1:10pm the day of departure. We actually have a view of the bay/ship from our home so the $7 cab ride was the quickest and easiest trip we've ever had to a cruise ship!
Spirit is a great ship...lovely atrium, staircases and dining rooms. We sailed her to Alaska a few years ago and the thrill remains the same. Second night was the first formal night.
Here's some info about the ports: Zihuatanejo, Ixtapa Mexico