We hiked Makapu'u Lighthouse Trail and Diamond Head. Neither are near Aulani though. We stayed two nights in Waikiki and one night on the North Shore before checking into Aulani for seven nights. That made it easier to see that side of the island. I've heard many on this board talk about the bad traffic. We never had any issues with traffic. Perhaps since we stayed at different places.
Both of those trails were really nice! Makepu'u was paved the entire way, but still kinda steep so it was still a workout. But plenty of kids were doing it too. A couple older people were out there and looked like they were struggling though. The views from the top were beautiful! And Diamond Head was amazing. Definitely a little harder, but worth it!