We go on road trips all the time and the pups love it. Just think of the things you use everyday and plan for the weather that you will be seeing. We go up to B.C. a lot and bring jackets and sweaters for them in the winter because it's so cold and wet there. If you are going to the beach, plan for warm weather with extra water and a lifejacket if you plan on getting in the water.
After a couple trips, you will figure out what you really need to pack and will have more of a routine. My two absolutely love going on trips with us and we all have a lot of fun