Pick these guys!
I did a ton of research and, with the Four Seasons' help, picked these guys. They were a fun, incredibly friendly, attentive group. There's a biologist on board who snorkels beside you, pointing out fish and telling you their names, as well as a certified scuba instructor.
Molokini was beautiful and amazing, but the most amazing thing EVER is swimming with wild sea turtles (we saw 3!). Put that on your must-experience-in-life list. Breathtaking.
The ride was smooth (no seasickness here, and I'm prone to it), the lunch was good and simple (make-your-own sandwiches, salads, and chips), and the mai tais were, hands-down, the best I had my entire honeymoon. Really. Pick these guys.