California has some complicated commission with equal numbers of registered Democrats and registered Republicans.
Anyways, yes, those PA, OH, and MI governor races are important. If the Democrat wins, they can block some extreme Republican gerrymander. The main reason that the Republicans have the legislature in those states is their gerrymander.
The commission only draws state legislative district lines, not congressional ones. So the GOP needs to hold the governorship, to effect split party control of the process. Whitman I think has a reasonable chance with her deep pockets, and because I don't think Brown is well positioned to run in an environment where the state is effectively BK.