All routes:

 Ride from Evans to the Berkeley BART station.  Take BART to the Hayward 
station.  From the Hayward station, go east on 'A' Street for about 1 mile.
Turn right on Grove Way.  Grove Way becomes Crow Canyon Road after about
1 mile.  Continue along Crow Canyon Road until it hits San Ramon Valley
Boulevard (about 8 miles).  Crow Canyon Road is a gradual climb for most
of its length; don't push yourself too hard early on.
 Turn left on San Ramon Valley Road.  Take San Ramon Valley Road about
4 miles to Diablo Street in Danville.

Easy route:

Continue along San Ramon Valley Road (becomes Danville Boulevard).  This
road gradually declines all the way into Walnut Creek; enjoy it.  Take it
about 6 more miles into Walnut Creek.  After you go under the freeway,
it's about one more mile to Ygnatio Valley Road.  Turn left, the
Walnut Creek BART station is on your right 2 blocks up.  Total riding
about 20 miles.

Intermediate+Advanced routes:

Turn right on Diablo Street.  Take it up to Mount Diablo Scenic Boulevard;
turn right.  Turn left on South Gate Road.  South Gate Road averages
about a 5% grade for about 3 miles.  It's a really nice ride, especially
if the weather is clear, but don't blow yourself out too early.  Take
South Gate Road until it meets Summit Road and North Gate Road.

Intermediate route:

Go through the intersection and descend on North Gate Road.  There are
some sharp turns which require braking on North Gate Road; be prepared.
North Gate Road becomes Walnut Avenue, which runs into Ygnacio Valley
Road after about 10 miles.  Turn left on Ygnacio Valley Road and take it
into Walnut Creek.  The BART station is on your right after you pass Main
Street.  Total riding is 25-30 miles.

Advanced route:

Turn right on Summit Road.  Summit Road averages about a 7% grade for 2-3
miles, but it's a very rewarding climb.  The last big is a footpath that
I usually find too steep to ride up, but someone on a lighter bike might
want to; it's only about 100 feet.  Hang out at the top, have a drink and
a snack while your pulse calms down a little.  Descend Summit Road
back to the intersection of South and North Gate roads; turn right on 
North Gate Road.  North Gate Road becomes Walnut Avenue, which runs into
Ygnacio Valley Road after about 10 miles.  Turn left on Ygnacio Valley
Road and take it into Walnut Creek.  The BART station is on your right after
you pass Main Street.  Total riding is 30-35 miles.