I've never done it myself as I have a pad on Oahu and always ride to the airport and back, but walking from HNL to a very awesome, yet frequently overlooked Tiki Bar Restaurant called "La Mariana Sailing Club" (Marina, Bar, Restaurant, and Gift Shop) would IMO be well worth the hoof. It's probably a 10 minute ride with traffic, and I'd say a 30-40 minute walk depending on your pace. If you could swim across the water from the airport, you'd be there in 10 minutes.
The hardest part would be walking on Nimitz, but there are sidewalks most of the way.
Eventually, Honolulu may put in the much anticipated airport to downtown train. Until then, it's "The Bus", taxi or walking.
http://www.lamarianasailingclub.com/
I don't anticipate anyone laying over in HNL unless it's inter-island. If you are flying to say, Maui, and have a 5 hour layover in HNL, rather than sit at the airport, I'd definitely check out La Mariana.