I'm an operator on Kauai and highly suggest "Dive Maui"
www.goscubadivemaui.com, super solid crew! Request Capt James Begeman, he has years of experience in Hawaiian waters and is a whale guru, he'll rock your surface interval! I worked under him on Kona Aggressor and is one of the safest captain I've met. CJ and the rest of the crew will show you Maui underwater better than most. There are a lot of great shops on Maui, but Dive Maui is who I send my customers headed to Maui from Kauai.
Also PM me if you have questions about maui non diving things to do. I've spent a lot of mini vacations over there.