If you want land, stop looking at the island and the BART apartments. Alamo, Diablo, Reliez Valley, Fairview, the Lafayette hills, Knightsen, Byron, and Sunol are the conversations. Briones and Canyon are the rural extreme.
Large lots in this region come with fire, wells or old infrastructure, and a car. They do not come with a walk to dinner, unless you count Danville or Lafayette as close enough.
Towns
San Ramon Valley
Alamo
Unincorporated, leafy, and deliberately low-key.
OpenCentral Contra Costa
Reliez Valley
A wooded valley of houses above Lafayette.
OpenSouthern Alameda
Fairview
Hill neighborhoods above Hayward.
OpenDelta & East County
Knightsen
Horses, fields, and a rural pace east of Brentwood.
OpenDelta & East County
Byron
Hot, rural, and on the way to the airport and the orchards.
OpenTri-Valley
Sunol
A tiny town, a water temple, and a railroad in the hills.
OpenSan Ramon Valley
Diablo
A tiny community on the flank of the mountain.
Open