Where is a good place to start when planning a road trip?

Plan every hotel in advance. You won't be allowed to stay at very many. 90% of hotels are 21+. Do not book through priceline or any of the 3rd party sites that don't allow you to pick your hotel in advance. I just watched a 19 year old get turned down after driving 3 hours to my hotel. And then we told him that no hotels in the area were 18+. He had to drive 10 miles to get to a hotel that would check him in. Mapquest and your car's MPG ratio should help you estimate gas costs, which are much higher in Cali. You'll have to figure in money for food, tourist traps (more fun on road trips), hotel costs, and give yourself a good cushion for spending money. You'd be surprised how quick it goes. Break the costs down day by day and it will make it easier to know how much to bring.