We had a wonderful boat trip up the Na Pali coast with Captain Bob's boat and crew. The comfortable motorized catamaran (carrying no more than 16 passengers, so never crowded) leaves from Anini Beach, about 10 minutes east of Hanalei Bay, and goes up the coast for more than an hour, stopping at and entering cool caves with waterfalls and terminating at a reef where you can enjoy about an hour's worth of snorkeling in five- to 25-foot waters. They provide excellent sandwiches and beverages, along with the snorkeling gear, as well as very good tour guide info.
The Na Pali coast is one of the most beautiful places on earth, certainly, with verdant cathedral-like spires towering over the unbelievable azure of the Pacific crashing against the rocks in gorgeous sunshine. It's mind-blowing.
We also drove along with a pod of dolphins on the way back, perhaps a hundred together, and we saw sea turtles in the reef at Anini. Awesome!
I cannot pretend to compare this company with others, since this is the only such boat trip we went on. But I think most of the companies are about the same price and the same kind of trip. However, we saw some inflatable boats stuffed full of people in what looked like uncomfortable cramped quarters and were glad to be aboard our comparatively cushy catamaran.
In any case, I highly recommend Na Pali Sea Breeze.