I think that's how it worked out with my two, almost DD16 and DS13 when we went. Our first 9 days (Waikiki and cruise) were pretty much go every day, and by then, they were ready to do some chillaxing
Our last 5 days were at Aulani, and we only left twice.
My kids really enjoyed surfing (Waikiki)!! Their second favorite was snorkeling (Hanauma Bay and Sharks Cove) the most. Because we'd been those places (plusvin Kauai), they didn't want to do Rainbow Reef. There are tons of fish in there, though, so give it a shot if you don't elsewhere. We hiked Diamond Head, and it was much easier for them than us LOL; they enjoyed it. We also did Pearl Harbor and the swap meet, which they enjoyed. They didn't want to do the stand-up paddleboarding at Aulani, but they do that at the lake at home. Would be a fun teen activity without leaving the resort. They both actually really enjoyed making kukui nut leis one afternoon on our cruise (even the boy), so that might be an activity they'd like. Mine didn't want to do any of the teen stuff, but again, we were pretty tired by then LOL. (Well, DD and I did the menehune hunt some...) They were really content lounging, doing the slides, hanging in the pool, and especially floating in the lazy river (sometimes together, sometimes alone, sometimes while playing on their phones....whatever!). And actually, I was too!! We did Paradise Cove luau, and they enjoyed all the activities before it, especially the canoe ride and tattoos. Our other two tries at a canoe ride got cancelled, but I couldn't pay what Aulani wanted, so we just did the free one at the luau and it was fun. We also explored Secret Beach a couple of times and looked for turtles at Paradise Cove, so little hour-long "excursions" and then back to the lazy river
That ended up being way longer than I meant! Hope some of that helps!