Lots of space/trails in MV itself. Check out the Stevens Creek Trail -- it runs very close to YC and goes for a good 3/4 miles. You can find lots of people walking, running with their dogs. If you want a big house with a big lawn etc. you can move to Los Altos, lower prices with huge lawns. Also, if you just drive about 20-30 mins west from MV, the hills with lots of greenery are there, another 15 mins drive will take you to the Ocean.