Do you have/need a USA ESTA for the MIA stop? You say 24 hours, but it's unclear whether this means just under or just over 24 hours, as the former would be a connection and the latter a stopover. Also, if you'll have checked bags, chances are that the airline won't check them through for an overnight connection in the USA over about (I'm guessing on the threshold) ten hours and certainly not for a stopover, so you might need to go through USA immigration and customs just to deal with a checked bag, even if MIA currently permits international to international airside transit (I don't know the rule on this, but not many USA airports do).