Just got back from our very first trip to Kauai, Jan 12 to 26. We stayed at the Kauai Beach Villas in Lihue and were very glad we chose the "middle" for our first trip. We don't like moving so a week north and a week south, while it might be ideal, doesn't work for us.
We did a lot of sightseeing, even though it's a small island (compared to Hawaii where we usually go) to really see everything takes a while. We didn't have a really long drive on any day, and we liked that.
We had a lot of wind our first week, some cloud. Then one absolutely torrential day of rain, then great weather the second week. It is definitely hotter and drier on the south side of the island. North side is much more scenic.
YMMV, but I think that KBV or Pono Kai might be good choices for you with RCI. I posted sightings of some KBV weeks a few weeks ago in January, not sure if they're still there or not. That was for 2013. They bulkbank about a year ahead of time.