Wow! What a great little spot. So close to the beach and everything Waikiki has to offer. Sure, it's small, but you'r'e going to be spending most of your time out and about so it's a great spot to come back and get some shut-eye and make yourself a coffee in the morning. The place was really clean, the communication about check-in from Team Koa Kai was simple, and there was a book with some great local tips. Plus, that lanai is a great spot to watch the waves as the sun comes up.
There's an air-conditioner but I preferred to sleep with the fan on and the lanai door open. You do get a bit of noise, but you're in the middle of a big city so that's to be expected.
Really, I couldn't fault the Duke Penthouse and can't wait to come back!