I’ve been to both Conrads, but not the WA.

From California, Bora Bora really is a whole lot easier and cheaper (when not on points) to get to than the Madives, so I would bear that in mind. Those Bora Bora flights look a bit overpriced to me, they're more regularly $200 or so.

In terms of the two Conrads, they're both different and either would be reasonably good for your needs as a family. If I had to choose I'd probably say the smaller island in the Conrad Rangali Island was my favourite experience, but I'd rather go back to the Conrad Bora Bora than take a main island beach bungalow. In your shoes I'd probably do the Conrad Bora Bora because of the easier location, because you have off-resort options in Bora Bora (not a lot, but some), because the Maldives is undeniably even more couples focused than Bora Bora and because the main pool is quite nice with a well equipped pool boy setup with lots of fun things to do.