Cupertino (pop. 65,000) is situated up against the foothills of the Santa Cruz mountains. It is something of an anomaly being the one city in the South Bay that doesn't have a distinct town center or main street. It is home to Apple Inc. and a handful of other tech companies, a highly-rated local schools system and quiet neighborhoods.
It's 15 minutes west of San Jose and 45 minutes south of San Francisco. The nearest railway, Caltrain  (connecting San Francisco with Gilroy, stops in downtown Sunnyvale, about a ten minute drive from the city center.
Cupertino has 2 major streets: De Anza Blvd., which runs North-South, and Stevens Creek Blvd., which runs East-West. The intersection of these two streets is in the center of Cupertino, and most of the businesses and shopping centers in the city are located in the area.
Highways 85 and 280 cross through Cupertino. These provide excellent access to the western cities in the South Bay, and to downtown San Jose (respectively).
Public transportation in Cupertino, as is the case for much of Silicon Valley, is very poor due to the low population density and demographics of the region.
Traffic is not much of an issue and major streets come with bike lanes, so biking is relatively safe.
At the intersection of Highway 85 and Stevens Creek Blvd. is De Anza College, the community college for the area. It houses the Flint Center for the Performing Arts , where major events in the area take place. It is one of the largest community colleges in the area, and has an excellent reputation.
At the intersection of Highway 280 and De Anza Blvd. is One Infinite Loop, the headquarters of Apple, Inc. 
McClellan Ranch Park, on McClellan Rd. has an old farmhouse (with pigs!) and a short trail along the creek to walk. Cupertino also a bunch of suburban parks, notably Memorial Park on Stevens Creek Blvd. which has ponds with ducks.
Cupertino is served by a large regional enclosed mall, Vallco Fashion Park. It features Macy's, Sears, and JC Penney. Although the mall has seen better days, you can count on easy parking and no crowds. The mall is currently in the beginning stages of redevelopment, but will still keep the enclosed mall.
Apple's headquarters features "The Company Store." The store sells Apple logo merchandise not available at its standard retail stores, including t-shirts and small gifts, iPods and accessories, but does not sell most Apple hardware. It is open 10AM to 5:30PM Monday thru Friday, and closed on some American Holidays.
Be careful to check for ticks  after hiking in fields in the bay area. There is a high rate of lyme disease transmission in the Bay Area. If a bulls' eye rash develops at the tick bite site, immediately seek medical help and treatment with antibiotics.
Cupertino is very safe, with violent crime virtually nonexistent. On the other hand, this means the local sheriff's deputies have little to do but hide behind bushes to catch drivers for moving violations. Be sure to obey traffic laws while in Cupertino.