Galvanized pipe from 1964 in CA, surprises me. Are you certain? If it is,that is lkily the problem. Before doing anything drastic buy a pressure guage with hose threads at any big box. Testing at front outdoor hydrant,laundry and other hose fitted outlets can sometimes reveal the trouble.
You should detect color in water if iron pipes have corosion.

Galv. was typical in 64 as the transition to copper was in it's infancy, so the problems with the water will be corrected with a complete repipe, and PEX is becoming the standard.

A repipe, however, will not address the requirement for periodic snaking. That will only be addressed with changing the affected drain lines to the sizes currently required.

If you are on a raised foundation, it's fairly straight forward, on a slab, not economically feasible.

I too live in CA and had old Galv piping. I re-modeled the place last year and went with pex. I prefer copper, but the water is hard and low ph, so pex it is. Eliminating all the old piping has been great. The "ring around the toilet bowl" has disappeared. The aerators are clean. Be aware that running a lot of fittings on pex creates a lot of "bushings" which lead to pressure reduction. The inside diameter of a 1/2" pex fitting is about 5/16". Just be careful in your lay-out. Re-pipe. You will be happy with it.