The only really good target is Port Isolation. WC's are just going to be leader fodder for GoW elsewhere. A WC comes within 3 movement of any of their connected cities and we should assume it's dead.
IMO, we need to bleed ND and GoW's GA's off, mostly playing 'defensively'. (that can include Inchon type offensives) RP needs cities on Bob, but we really don't. If worst comes to worst, we could give RP Vox's old land so they can make it productive, and just fight free from any city ties on Bob. It's not so much important that we control the land, as that ND/GoW don't.
Of course if we can keep RP around in Spain, fight off GoW/ND, and have RP set up for a good GA about the time GoW/ND leave theirs, it makes things a lot easier. That's why I think we should focus almost everything we have to defense of RP right now. Units in the N just need to block landing sites and prepare for when we have an excess in the S and can begin making inroads in the N.