When we fly, we are a carry on family. We want to make sure that bag is on our flight and makes every connection and we don't want to pay an arm and leg for luggage.
Then when we get to port we leave almost all our carry on suitcases with the porters (kind of like checking them) and only carry on one or two backpacks.
I know some people think carry on size suitcase means it has to be "carried on at port too".