The cruise staff will tell you that Progreso is a spot to go to get to other places. That is true. It is definitely not as commercial as Cozumel, however, it is probably closer to what Mexico is really like. The people were very friendly and tried to sell you everything, but if you just say "no thank you" they will leaver you alone. We enjoyed walking around the open air market, and we rode the double decker bus. My boys enjoyed the bus!
We went to Dolphinaris that we booked through Carnival. It was a great experience. They were very good with my boys and worked hard to make the morning enjoyable. We got to touch the dolphin many times, give it a hug, kiss and ride on its belly. Lunch was included and was very good. They even had chicken nuggets for kids who may not want fajitas or quesadillas. They also refunded my 5 year old's ticket price since 5 and under are free. The credit was on my sign and sail account before we left port.