If you don't feel like doing the hills, the easiest way up to Danville is Foothill Blvd - the name changes and this becomes San Ramon then San Ramon Valley Blvd. From Main Street in downtown (such as it is) Sunol, just take one of the roads north (there's only two, one is by the train station) and then turn right onto Foothill. Only one wacky intersection (over I580), otherwise it's just a straight shot with good roads and mostly wide shoulders. Some folks don't like the narrow road as it winds through a couple of switchbacks at the top of the hill just outside Sunol, but as long as you don't hit it at rush hour it's fine and not very long. Getting to and throught the Pleasanton BART station can be frustrating, and is completely unnecessary. Plus, I really don't like riding the trail through San Ramon and Danville - too many intersections, too many people enjoying it to make it a worthwhile bike ride. IMHO.
For some parts of Danville, you'll be better off heading east on Crow Canyon towards Tassajara/Blackhawk rather than going into downtown, then back out on Sycamore Valley/Diablo/Tassajara.
Last edited by jonathanb715; 01-22-10 at 08:20 PM.