Why? You want a taste of almost everything America has to offer all jam-packed into one big state. California has destinations and attractions that are world-renowned and draw tourists from every corner of the globe. From the natural wonders of Yosemite to the cities of San Francisco and Los Angeles, if you can dream it, you can probably find it somewhere in California.
Where? California is the 3rd largest state in America and probably the most diverse in terms of natural and man-made landscapes. If you don’t have time to see it all (and no one has that much time), I’d suggest picking one area in each of three categories: city, park, and beach. San Francisco is compact, tourist-friendly, and great for history and architecture. Los Angeles is sprawling and tough to see without a car, but includes fabulous beaches and the very unique Hollywood area. San Diego is also a good, family-friendly city choice. The two parks that are most distinctly California are Yosemite and Death Valley. The awe-inspiring scenery of Yosemite actually helped create the National Park System and to this day draws throngs of visitors from around the world. Death Valley gives you a look at one of the most inhospitable landscapes in the lower 48 states, but for geology/desert fans or those lucky enough to visit during a wildflower bloom it’s a very magical place. As far as beaches go, you can find ones great for surfing up and down the coast, people watching around the Santa Monica area, sea-life watching in the central coast, or solitude in the northern reaches of the state. Pick one and grab a towel!
When? California has great weather year-round. It’s really never too hot, too cold, or too rainy to visit the Golden State. You’ll find larger crowds during the summer months in most places, especially Yosemite and the beaches. The beaches in Southern California are warm enough to enjoy year-round (the water is NEVER warm due to off-shore currents though) . The winter months bring cooler temperatures with snow and skiing in the mountains.
How much? California is one of the most expensive states to live in, and tourists will see many of those costs including some of the highest taxes in the country. Rental cars, hotels, and especially gas are well above the national average here. Great produce and fresh food can be had at reasonable rates, but restaurants usually have a large mark up. If you’re willing to stay a little ways away from the main sites or camp, you can definitely find deals. If you want to visit Disneyland, be prepared to drop over $100 per person per day on admission alone!
How long? To see all of California would probably take a lifetime. I lived in Los Angeles for 8 years and only saw a fraction of what the region had to offer. If you’ve only got one week, pick San Francisco + Yosemite OR Los Angeles + beaches + Death Valley. If you’ve got a couple of weeks you can make it to both some Southern and Central/Northern sites. The drive along the coast on Route 1 between LA and San Fran is a great choice if you’re willing to spend a couple of days enjoying the trip, then return in just 6 hours along I-5.
If you’ll have a car: Lonely Planet California’s Best Trips (Travel Guide)
If you won’t have a car: Lonely Planet California (Travel Guide)