@Sharon Tseung  I have dozens of clients from Ca, ( selling them more then 150 properties, about 450 overall  ) and many from Silicon Valley area  ( most  seem to be engineers)  .

frisco is still muy caliente, and I suspect the better areas of Silicon Valley/peninsula are as well.

Short story:Worked in Silicon Valley for 20yrs (San Jose, CA area) for IBM in the '70s. 

The duplex is a good configuration and in better class property/areas due well - - just try getting an SFR in San Fran :)  Silicon valley has a good population of dups & quads.Low-end class-c&d are typically fraught with issues.my $0.02

http://www.wsj.com/articles/facebooks-answer-to-silicon-valley-housing-crunch-build-apartments-1469534402

Here are some reference points my old division president shared with me when I had asked him about why he was so interested in Concord. " When business people reference California's "Bay Area” they most often think of the tech centers in San Francisco or Silicon Valley, but believe it or not, the East Bay was once the center of the Bay Area with the State Capital in the towns of Vallejo (1852) and Benicia (1853) before moving upriver in 1854 to where it now stands today in Sacramento.

I have been speaking with short-term furnished rental owners who rent to workers or other travelers, and operate near national parks like Yosemite, in urban areas like Oakland and San Francisco, the desert and coastal communities like Palm Springs and Venice Beach..THE COMMON THREAD IS THAT THEY TEND TO PULL IN 2-3 TIMES THE GROSS RENTS OF AN UNFURNISHED LONG-TERM RENTALI WOULD LIKE TO BRING TOGETHER AND HEAR FROM THE SHORT TERM RENTAL BP COMMUNITY ABOUT THEIR IDEAS, WHAT THEY ARE DOING/OPERATING, WHAT THEY ARE CONSIDERING BUYING OR OPERATING, AND ANY AND ALL DISCUSSIONS ABOUT SHORT TERM RENTALS.From vacation rentals w/ bikes and toys, to super-high-end corporate rentals for tech employees in Silicon Valley, to families near the lake, medical students or workers on rotation, and oil field workers who need a home away from home...THERE IS A NEED FOR ALTERNATIVE FORMS OF HOUSING FOR NICHE TYPES OF WORKERS AND TRAVELERS ALL OVER THE US AND THE WORLD.I have seen apartments, hippie trailers, house boats, towering castles, spectacular lofts, tiny homes, dirty couches, teepees, yurts, and impeccable $2MM+ homes and estates.

Happened in SF ... happened in Venice Silicon Beach, same with Portland Silicon Forest, same with Austin, etc.

So to that end, if I've done the work to "nail down" the next Silicon Valley, just for a ludicrous example, handing that information out like candy is only going to make things more expensive for me.

In fact I think more people will live in SF now if they don’t have to do daily 3 hour commutes to Silicon Valley (Mt View, Palo Alto etc).