I would drive in the day before then you are relaxed and ready for the cruise.
If you are delayed in traffic (not much between S.A. and Houston) but in Houston you could run into delays.
Check if there are any hotels that offer free parking for the duration of the cruise.
Alexandr Pushkin, Carnival-Holiday, HAL-(old)Westerdam, Orient lines-Marco Polo, Royal Olympic-Olympic, NCL-Dream, Dawn-Princess, ACCL-Grande Caribe, Oceania-Insignia (3), Regatta(4) Marina (1) St Lawrence Cruise Lines-Canadian Empress
Scenic River cruise June 11,2012