definately go all pvc, its worth it and will last a lifetime.
Is your home on pier and beam? If so, much of the re wire job is done under the home and above the rooms in the attic. All your re wiring can be done with out tearing down any walls.
matter of fact, much of the new wire can be added using the old as the "fish".
Get four of five estimates for this job as its expensive, but not a "arm and a leg".