Easy once you get on H1. Ask for directions from your rental car company to H1 as several are off site and it isn't quite as obvious how to turn around to get heading the correct direction (they sent us a different direction than the navigation on our phones and it was in fact, better than what the phone had us doing). After that, we used Google Maps to get us to Aulani, Costco, Target, etc. Easy.
I would anticipate some traffic if you arrive on a weekday. By the time you get bags, rent the car, and start driving you could be in the rush hour commute.