Before I was a geocacher, St. Joseph's Hill was one of my regular short hikes, and it's a popular place for hikers, joggers, and runners because it's so convenient to get to from downtown Los Gatos. Now I pick from a much greater variety of trails. But I did an after-work walk, a nice four mile loop with about a 750 foot hill climb, and it's an enjoyable walk, although you do need to watch out for high-speed bikers who pay no attention to the posted 15 mph downhill speed limit. Off-peak times may be more pleasant; on weekend mornings it is very busy.
You can start at the end of Jones Road, or on Alma Bridge Road by Lexington Reservoir.
There was once a cache at the top of hill, but that went missing some time ago.
The cache isn't exactly at the top of the hill. From the top, go slightly east and you'll see a little trail that goes behind some small trees. That's where you want to be. You're looking for a camo taped plastic peanut butter jar.
St. Joseph's Hill Open Space Preserve is one from a half-hour before sunrise until a half-hour after sunset.