Florida law states that if you are in a commercial vehicle (any hired vehicle that is licensed to transport passengers for a fee), you are not required to restrain a child in a car seat. However, if you rent a car, or have a friend/family member drive you in their vehicle then any child under the age of 5 years must be in an approved restraint.
My husband and I had the same argument re: car seats on vacation. I feel much more secure bringing my own car seats for our kids (though we don't use them on air planes). One time, my husband convinced me to leave ours at home and rent. I had very disappointing results with renting them (dirty, not in good repair, and no instructions with them, and no one at the rental place knew how they worked to help us) in London. We were very surprised by this. Not to mention, it was pretty expensive too. We now travel with our own (no more arguments from my husband, since it didn't work in London). We did buy a carseat carrier and a smaller "booster" type seat for our 4 year old for travel, and have generally both been happy. It was worth the extra expense for both of us, makes him happy to have a little less luggage then both of our full size carseats, we fit them both in the same car seat carrier luggage bag, and makes me happy to know my kids are safe for sure. For us, we won't be bringing them this trip, they'll be left in our car at the port. I can't imagine needing them this trip.
