Galveston is a good port as long as it is not in the winter (fog) and you really want to go to the Western Caribbean (and Cozumel) on a 7-day or less.
I am definitely not averse to any other ports - Fla east cost would also be good for me as I have family in the area (saves on hotel ).
Also not averse to any other port, as long as a ship sails out of it!!
I think, though, my wife may have a problem with Carnival. In her words, "I am never going back on that line".
It's a shame, though, because Magic is a great ship.
That does look like a fine itinerary too.