The kids did come down with colds around the beginning of the trip which matured into full-blown sniffles, sneezes and coughs by Saturday. We decided to cut the trip short by a day and head home Sunday so everyone could rest up. A little dramamine for the ride home cured the car-sickness issues. Dramamine is amazingly cheap... good investment for any long car ride.
The best part of the trip for the kids was getting to go to the beach every day, usually several times a day. They had fun running from the waves, collecting "treasures" (aka rocks), and looking for starfish. Maybe next time we'll be able to enjoy it in good health.