Vandernberg is generally used for highly inclined orbits or polar orbit launches. The earth's rotation is used to assist eastbound launches for equatorial/geostationary, so eastbound is preferred. Such as most of the launches from Florida and Wallops.

One of the weird bits of space trivia is that Israel's domestic rocket and satellite launch program makes the sacrifice of less efficient launches and less total delta-v in the first and second stages, by launching westbound over the ocean, because they really do not want to launch what is almost indistinguishable from a ballistic missile eastbound over their angry neighbors. Pretty much the only place in the world where low-inclination launches occur westbound.