French Polynesia vs. Cook Islands?

I’ve never been to the South Pacific, so I’m curious as to which of these would be a better destination.

In terms of price, Cook Islands seem to be a better deal—but would it be a situation of “getting what I bargained for?” or is French Polynesia just overpriced?

From my research, going to either island groups yield about the same results in terms of things to do, climate, etc.  I’m just wanting a relaxing island vacation with opportunities to snorkel, sunbathe, shop, and well, relax.  I'm potentially going March or June of 2012 (depending on school schedule).

Which would be better between these two or are the equal?