That is the same on Ka'anapali Beach too. We arrived late one evening because of a schedule change by the airlines. We were hungry and hoped that we would find a restaurant open somewhere on the Ka'anapali Beach path but everything was closed except one place very close. We found out about that later but I still don't know where exactly it is. We didn't enter the big hotels where they may have bars open still later at night.
You would have to drive to Lahaina to find something open later than 10 PM but you will have to drive back to your resort about four miles. I Googled and found this website that should be very helpful. They have them on the coffee table at most resorts and some others magazines too.
Tourists in Hawaii seem to go to bed early but rise early too. Very different from Honolulu on Waikiki Beach where tourists are out late at night. Oahu Island is beautiful and lush too. There was a thread about it very recently with some photos. There are lots of honeymooners on Waikiki and Ka'anapali Beach. I would land on one island and depart from the second so you see both.