We just returned from our June 25 - July 2 cruise on the Carnival Conquest.
This was our 3rd cruise in 3 years, all with Carnival (Elation/Galveston June 2004, Conquest/New Orleans June 2005, Conquest/Galveston June 2006.) My family (myself (46), wife (45), daughter (17), and son (12) all had a GREAT time on the Carnival Conquest!
We drove from San Antonio to Galveston which is about 4.5 hours. The port is easy to find and fairly well organized. We used "Lighthouse Parking" which is just a 1/2 block off the main road and cost $55 for the week. They take you and your luggage to/from the terminal. NOTE: Upon returning we learned that Galveston started enforcing a tariff on buses/taxis,limos that was passed 18 months ago. They must now pay $10 per entry to the port, so might be going up after this week.