Sounds like a great trip. I have dove both PV and Cabo. I think Cabo is your best bet because the dive sites are within 10min boat ride of the cruise ship. My favourite sites are Sea Lion rock and across the bay. You will see lots of fish, eels, rays, porcupine fish, white tip reef sharks (if you are lucky) but not much for soft coral.
PV seems to have the same type of underwater terrain and fish but you might have the chance of seeing mantas(in the right season).
The dive sites were at least 1 hour from the PV dock - I really liked Las Marietas but it was 1 hr 30 mins from the cruise ship dock. Los Arcos in PV is about 30 mins but not worth the effort to get there. Los Arcos in Cabo is beautiful above water.
The water temp in both PV and Cabo is chilly in the winter high 60s. I wore a 3mm shortie, 3mm long and a hood and was toasty but the DM only had a 3mm long and froze. Have haven't been to Manzanillo but would love to go.
As far as dive ops go, I dove with Pacific Scuba in PV. I have dove many times with Amigos Del Mar in Cabo. ADM has well kept rental gear (Scubapro regs, Aqualung BCs) and a nice wide boat to dive from but sometimes the DMs can be difficult. Both Amigos Del Mar and Manta Dive are right by the cruise ship dock in Cabo. Have fun! :bounce1: