Depends what you want to catch really. Snapper and gurnard are supposedly caught at South Beach, from the South Mole back along the beach. Look for pipi beds. Access through Putiki from memory. There used to be pipi beds at the northen end of castlecliff down the access points at Karaka/longbeach rd (cant remember now). Could try there. Santoft beach through the forest is also supposed to be ok as well.
Plenty of kahawai and red cod in winter at the North Mole River mouth if you can get a spot.

Your limiting your self with bait a bit using just squid really. Try pilchard and fresh bonito and tie it on to your hooks. Wanganui was and probably still is a repository for crabs (like here) so use floats when your baits are disapearing. A lot of snapper get caught early morning along there Ive heard, so dusk and dawn are the times really. And yep try crab for bait too. There will be plenty of lemonfish along there.