Most major airlines will fly into George H. W. Bush Intercontinental Airport (IAH), which is on the north side of Houston, or about 60 miles from the port of Galveston. Another option is to fly into Hobby Airport (HOU), but not many airlines use this airport. It is closer to the port, though.
if you fly in the day of the sail you can book a seat on the bus from the cruise line-
if you are coming in the day before or earlier you can either rent a car from hertrz or enterprise-they are the only rental companies with an office in galveston- or you can hire a chauffered town car or you can get on a van usually from the same company that rents towncars