The biggest thing that helps the bay area be bike friendly? Bike + Transit.
See, any out-of-shape individual can bike about 5 miles at a light level of effort in street clothes and not arrive really tired at work nor need to shower afterwards (Assuming effective deodorant use :D). So does that mean that you need to live 5 miles from work?
Naw! Just use one of the bike-friendly transportation systems and work that into your commute. It's a multiplier. The south bay is not dense enough to have a truly convenient mass-transit system, so unless you live right next to a station, you wouldn't be able to make use of it without a bike. And without mass transit, it's a huge adjustment to bike that far. But with VTA and Caltrain, they've got a reasonable number of internal bike racks in every train so you can just rack your bike up inside the train and pop out 10+ miles away.
A lot of the other transit systems have some level of bike accommodation, usually a rack on the front. BART lets you take a bike on the train... but bans bikes from the train during certain hours. MUNI light rail forbids bikes entirely.
Why transit planners are so agog over BART completely escapes me. BART trains have to be custom made, it was designed around how they wanted to build a mass transit system in the 60s (and provided many lessons for follow-on transit systems), and is at the point-of-least-usefulness between light rail and commuter rail.
The goal is for the Stevens Creek Trail is to extend all the way from where Stevens Creek hits the bay to the santa cruz mountains. A good sized chunk of it through Mountain View is already done and it keeps creeping uphill. Right now, it starts at the bay and extends to El Camino Real. I'm really excited about the next segment that will connect to Sleeper so I can have an even longer portion of my commute to work away from traffic.
This is a chunk of my commute every day and also the jumping off point for lots of recreational rides. It connects to the bay trail around Moffett Field and adjoins a bunch of parks. It's also got convenient endpoints situated along several VTA light rail stops.
The goal for the bay trail is to circle all the way around the San Francisco bay. It's not done yet, mind you, and some parts are unpaved. The gap I notice most around Moffett Field. You end up needing to take a bunch of surface streets to get around Moffett / Lockheed Martin / Onizuka AFB and it's kinda annoying. They've finally worked out a good agreement about where the new segment is going to be.
North of Moffett, it stretches a good ways up the coast, past the Stevens Creek Trail connection and through Shoreline Park and into the Palo Alto Baylands preserve and you can see plenty of shorebirds and power lines and you end up in East Palo Alto where there's a gap in the trail before it can reach the Dumbarton Bridge. South of Moffett, it goes through the Sunnyvale Baylands Park with a loop around the bay and then heads towards Alviso with a connection to Great America and a new connection to the Guadalupe River trail where there's a dirt loop before you reach another gap in the trail.
The loop comes tantalizingly close to the ghost town of Drawbridge.