The city itself is deceptively ordinary, statistically so normal it's a favourite venue for market-testing movies made down in Hollywood. But you sense it is really very weird, and that some time, some place, the delicious undercurrent of barminess that wafts through moneyed America will surface.
Look for a sign advertising "The Largest Flea Market in North America". Imagine 2,000 stalls selling "Face It - Elvis is Dead!" T-shirts. Hang around a bit and a sharp-booted dude might try to sell you a pistol wrapped in a brown bag. Then go for a drive down Park Avenue. Savour its serene grid of residential tweedom complete with matching lawn sprinklers. Suddenly, you enter a campus full of obelisks and ancient Egyptian hippo-deities. There are papyrus groves and lotus columns, and a leggy blonde invites you to step inside her tomb. Surely you knew San Jose was the headquarters of American Rosicrucianism?
And what about the techno-boffins? Gone hiking and biking, I'm afraid. Flown up to Lake Tahoe for the weekend. But you can follow their story in the Tech Museum of Innovation. This is the place to muse upon the birth of bar codes. There's a CD-Rom Infolounge full of virtually real kids, and a machine that will count your dust particles.
When you've had enough of the hi-tech present, visit the house that Sarah built. This is a 160-room Addams Family-style residence built by the reclusive daughter-in-law of Mr Winchester Rifles. It was a vain attempt to appease the spirits of people killed and injured by the company's firearms.
It all started in 1884, when Sarah Winchester, mortified by the deaths of her month-old daughter and then her husband, sought solace in a Boston psychic. According to the news from the netherworld, the only way to placate the marauding souls of the thousands killed by the gun that won the West was to head out there and build a house so convoluted and never-ending that the good spirits would be accommodated and the bad get lost.
So that year the 46-year-old ghostbuster took her $20m fortune off to California, and bought herself a farmhouse near San Jose. Then she hired a team of carpenters, who worked round the clock for the next 38 years constructing a paranoia pile that is today known as the Winchester Mystery House.
It's a spooky mayhem of a place, with "skylights" in the floor and chimney breasts that stop short of the roof. Flights of steps are two inches high, staircases rise into the ceiling. Doors lead into thin air, cupboards open straight on to plaster. To cap it all, my mile-long tour was conducted by a deadpan man wearing a Top Gun boiler suit and a neckful of love bites.
After such weirdness, San Jose's night life comes as a zany relief. Try the Sports City Cafe, backed by the revered 49ers football team, where the diversions include Bladder Buster's Night (cheap beer till you scream for the rest room), no-hands spaghetti-eating contests, and games of human darts and skittles. Or hit the Saddle Rack night club, where blue-jeaned babes break into spontaneous formation dancing, and macho Spanish boys queue to lie back in a barber's chair and swallow rivers of tequila poured high from the bottle by gleeful cowgirls. Then head back to San Francisco for a little peace and quiet.
How to get there: San Jose has no direct flights from the UK. Trailfinders (0171-937 5400) has a fare of pounds 358 (including tax) on American Airlines via Los Angeles; travelling on a Friday, Saturday or Sunday incurs a supplement of pounds 8 each way. Alternatively, you could fly non-stop to San Francisco airport, an hour away from San Jose. Flightbookers (0171- 757 2000) has a fare of pounds 295 on Virgin Atlantic - weekend supplement pounds 10 each way. Fares are likely to rise steeply from the beginning of April.
How to get around: You can survive without a car; the public transport system of trams and buses is inexpensive and efficient.
Who to ask: California Tourism (0891 200278); San Jose Convention and Visitors' Bureau (001 408 295 9600; it helps if you have a touch-tone phone).