Since almost all of the Hawaiian islands have whale watching cruises, you should know that the most important place is Lahaina Maui. For about $20 you can take a half hour cruise for whale watching. The season begins in December when the humpback whales migrate from Alaska and it ends in April and May.
Whaler's Village is next to the Kaanapali Beach Mall. It is possible to buy souvenirs and local crafts or have some lunch or dinner in the food court, but the funny thing is the "whale museum". Keep an eye on the prices, which can be a little high.