We have been on five Disney cruises and don't have any stamps on our passports.
Yes, I think you're right. You probably won't get a stamp on a trip to the Caribbean. I've been to Mexico many times, and only one time did I get a stamp on the way back, and that was from a flight from Mexico City to Ohare. Usually, we flew from Ohare to GWB International in Dallas, then to Chihuahua. We got stamps at the Chihuahua airport, but not coming back home.
I've got stamps from Brazil, Mexico, Korea, China, and Japan in my passport. I've got several visas stamped into my passport as well.