I sailed on the Carnival Conquest out of Galveston on February 24. Cruising with me were a friend and my parents, both of whom are in their mid 80's. We left Dallas early Sunday morning, because others who had done this cruise assured me that we would arrive in plenty of time (and we did), but for a perpetual worrier like me, I think driving down the night before would be money well spent for the peace of mind.
If you are parking in the Port of Galveston parking lot, check their on-line site. They give free parking to disabled vets and Purple Heart recipients. My dad received a Purple Heart in World War II, so the free parking was a nice perk.
Lines at check in went very quickly. Everyone was polite and friendly, and once we got on board we went to the Lido deck for a quick snack to hold us until dinner. We had access to our rooms almost immediately. We had an inside cabin, which was surprisingly roomy. If you travel with clothes that need to be hung up, you better bring your own hangers because there were only 2 in each closet in the cabin. After the lifeboat drill we spent some time looking around the ship, and then dressed for the early sitting for dinner. For those of you who like a glass of wine before dinner, Carnival allows you to bring one bottle of wine or champagne on board at the port of embarkation.