The North Shore (Princeville, Hanalei) is by far the most beautiful part of Kauai. Anyone who thinks Princeville is "sterile" must be blind. But if you like sun and dry, head for Poipu...which is far too touristy for my taste.

I think you could call the mega-condo plateau that is the Princeville resort area sterile and expensive. The Hanalei area is far preferable.
I, too, do not like Poipu. The beach is not that great. The snorkeling is not that great. It is just full of more condos.

Actually, while Kapaa itself tends to be exposed and windswept pretty much all of the time, and plagued by gross overdevelopment and brutal traffic, it's an easy drive south and west to better things. You'll want to go to Waimea Canyon in any case, and it's less brutal to get there and back from Kapaa than from Hanalei by far. And contrary to the notion that Poipu has poor snorkeling, Prince Kuhio, the tiny patch of sand just east of Kuhio Shores condos, is the best place I know of on Kauai for guaranteed turtles in quantity, and Koloa Landing has excellent (for Hawaii) snorkeling as well.
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Going north, there are no huge thrills before Kilauea, after which everything but Princeville is more or less excellent. Tunnels and Ke'e are the nicest beaches up that way for snorkeling. The reality of Kauai is that either the north or south is probably experiencing heavy winds and surf on any given day, so being on the East Coast lets you check the weather, and avoid the windward shore.
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Buy the "Ultimate Kauai Guidebook" for a great overview of pretty much everything. For a great but pricey meal in uninspired surroundings, try "A Pacific Cafe". For excellent food with the view that you came to Kauai for, book a railing table at the Bali Hai Restaurant in the Hanalei Bay Resort in Princeville.

we spent a week on kauai about 3 years ago and we did stay on the east side. we absolutely loved it! we're not big fans of huge resorts though. we rented a condo for a week for a great rate. it had an ocean view and we could walk down to the beach in just minutes. it was great. we loved the location, being able to see the north shore and the south without having to drive the entire island. a couple of our tours departed from the south so we were glad we didnt' stay north. we ventured up to princeville for a bit and did some shopping. but when we saw it up there, and saw how lavish all the resorts were, we were glad we didn't stay up there. it just wasn't for us. but that doesn't mean it's bad. we went in may, first week of may. so not too far off from when you're going. and we visited beach closeby to where we were staying and we didnt' think bad of it at all. it was just fine for us. i wish i could remember the place we stayed at! sounds like the exact vicinity you're going to be at. the only thing we would do different is save money and actually not stay on the ocean. but that's us. we rented a car and visited the beach and took tours. we didn't feel like we had to sleep next to the ocean and it is much cheaper not to do so. but it was our first time and it was beautiful! and we probably could've done without the kitchen. groceries there are SO expensive that we didn't end up buying and cooking much.
hope you have a great time! we can't wait to get back!!!

We are planning on going to Kauai mid December for 2 weeks. What is the weather like on the North Shore? We definitely want sun.
Thanks

Then don't go to Kauai in December, especially the North Shore. Seas willbe high, and a little or a lot of rain could fall daily. Poipu will be drier, but for the driest area of the Islands with sun extremely likely, the Kona and Kohala Coasts of the Big Island would be the choice. I'd go to Kauau in any case, but it could be cooler and damper than what you're looking for.