The lovely Miss Lynn and I have done FP on both PG and Mariner. It's Mariner hands down! We did the standard 7 night PG in Cat B(a very expensive cruise IMHO) and did FP on the 26 night Mariner cruise SFO-SFO in Cat C. You don't do Taha'a on Mariner though, so no Motu Mahana and no motu in Bora Bora.