we are a couple travelling first time to USA in mid Sept 2013.. we want to cover both the coasts in 18-20 days!! we arrive in NYC. we want to spend atleast a week in New York, go to Washington DC. visit Disney world, las Vegas and grand canyon! someone suggested we should visit San Francisco too! could you please advise on best routes to take. we do not mind driving. we are on a tight budget!! whats the cheapest way to fly from one coast to another. suggestions for places to visit and hotels etc would be really helpful!