California is the most visited state in the United States, Disneyland is the United States' second most visited theme park, and California's national parks attract almost 30 million visitors a year. Los Angeles--as the fourth largest destination for domestic travel in the U.S. and the second-ranked destination for overseas visitors, behind only New York--welcomed 25 million visitors in 2008. San Francisco is ranked in the top 10 most visited US cities,...