I work at a resort on the beach in Kaanapali, and where we're at (right by Whalers Village) and up to black rock the beach erosion isn't really any worse than it's ever been. Further "north" it's more obvious, was at Napili last weekend and the beach is STEEP there right now. Kaanapali, you're fine.
That being said, Wailea Marriott is a great option because Wailea beach is in great shape right now as well, love that beach too.
Friends don't let friends stay on Oahu.......... :-) Maui No Ka Oi