We had a wonderful day in Mazatlan this past May. We did not do an official ship excursion we explored on our own, very easy and much cheaper.
1st thing we did, get off the ship right away when it docks. Pass through the building that leads you out to taxi area. There are open aired cabs with little canopies on them, those are the ones you want. They will take you where you want, or they will give you a tour for a very reasonable price. A much better tour than you get on a formal excursion..because the tour buses can't go up in the hills where you get the great views. We loved our taxi tour, the driver/guide was excellent. He stopped let us out whenever we wanted, stopped for any photos we wanted..it was outstanding. He gave us pointers, places to eat, where to and not to shop. He did not lead us wrong once with any of his recommendations.
We saw all the monuments, statues, points of interest, etc that we had seen while researching what to do and see in Mazatlan. The cathedral is a must see.
When our tour was over he took us to the Golden Zone, where we were originally planning on going before he offered us the tour. He dropped us at the far side and said easiest to work our way back and said there would be plenty of taxi's whenever we were ready. He wasn't kidding either.
We shopped our way back, stopped in a little sidewalk cantina for lime margaritas and chips/guacamole. Went to Panama restaurant for lunch. Of course the jewelry stores had wonderful prices so we spent money there..lol.
You will really enjoy Mazatlan..the people are great, food is wonderful. We had a blast.