Puka dogs are delicious in an almost puni sort of way
Shaved ice is stupid and gross
Great cheap poke: sleeping giant grill in wailua
Great coffee everywhere
Beaches everywhere range from medium to excellent based on these factors:
-How many derps are everywhere derping around?
-how good are the waves for bodysurfing or whatever you plan on doing?
-what is the sand to rock/coral ratio (foot comfort awareness)
-what's the scenery like?
Polihale is sparsely populated, really great waves, and has zero rocks/coral to damage your fragile midwestern feet. You have to drive 20 mins on a gravel road which may seem like a bad idea but I saw tlb rentals doing it. Amaze cliff views bc it's like at the start of na pali coast.
Golfing at wailua is like $40, amaze course with like 6 beach holes
Do either a helo tour or boat tour of na pali coast. I recommend kauai sea tours. It's like $150 for about 6 hrs of snorkeling, the amaze coast views, dinner, and all you can slam mai tais. There are other tour companies as well, I'm sure they're all good
Hike at least part of one of the wailea canyon trails depending on your desire to descend/climb a bunch. But there's goats and stuff everywhere which is pretty hilarious, and some great views of the canyon periodically
Our group went to costco for breakfast food and beach snacks, ate out for occasional dinner or whatever. Sampler packs of HI beers for days. Just go explore and see stuff.