Best area and hotel in Kauai mid October

We are traveling to Kauai Oct 15-22 and are wondering what are the best areas and hotels to stay in? Also, since it is October is there a side of the island that will have calmer water for swimming?

1. We’d like a nice hotel with a view. Budget is 350/night
2. On a beach with swimmable water at this time in October is preferred but not a dealbreaker
3. Gym at the hotel

We would like to see the north shore just not sure if it is better to stay there or another side? This will be our first time so are not familiar with the areas or things to do.