Are you there for more than one dinner? If so, make it Merriman's (I've had great service in Waimea and the chocolate purse dessert is excellent) and Daniel Thiebault. Cafe Pesto is good, but not in the same league as the other two. Have a wonderful birthday!
BTW, here's a little story about a recent experience a friend of mine had at Merriman's that will give you some idea of the service. I had recommended the restaurant to her and told her she had to have the chocolate purse. Well, she went for lunch and was told they don't make the purses at lunch. She told the waiter she was so disappointed because that was her last day there and she'd come all the way just to have the purse. He winked and said, "Let me see what I can do." He came back and said the kitchen would be very happy to make a special chocolate purse for her, and they did.