If you are both surfers, why not go to the north shore, and stay at the Hanalei Bay Resort. There are a few kids, but not like the hotels.Otherwise, look for a nice quiet B AND B, on the south shore. Aloha……….

Kauai Inn is quiet, pretty & down to earth and you can get to Poipu fairly easy from there. I stayed there a few years ago and the owners are great people. They have treats out by the pool, bowls of tropical fruit and orange juice & pastries on the weekends. You can also ask the Inn about accomodations in Poipu. The hoteliers have a property called the Poipu Inn and vacation rentals, some with ocean views (beach houses) in Poipu.

The kauai inn is at 2430 Halemalu Rd. 800 808-2530

If you are both surfers then the place you want is on the east side, not Poipu. I love Poipu, but it better for snorkeling and body surfing. About ten minutes north of Lihue there is a stretch of beaches with some real good breaks.
But since Kauai is so small, you can pretty much stay anywhere and be at any part of the island withing 45 minutes. My recommendation for lodging would be to find a bed and breakfast that is inland just a bit. That will keep more of the touristy folks away from you. Kapaa has some nice areas, as does Waimea.
Hope you are able to find just the right spot for it. Good luck in your marriage, remember to listen to each other, and voice your own concerns.