We've been to CN 3 times and CSA twice, and our next trip will be to CSA. We loved CN the times we were there, but once we visited CSA, we found that it was an even better fit for us!
Both resorts have a great beach, but CN is located in a bay, while CSA is located on 7 mile beach. Basically what this means is that walking along the beach at CN is limited (while still quite long -- they share the beach with a couple of other resorts) -- the beach at CSA is public, and goes on and on and on (we still haven't walked as far as we could on that beach).
For us, we liked walking on the beach and seeing different things/people. We walked over to Margaritaville just to check it out. From CN you can take a bus to Margaritaville if you wanted to visit.. but it was nice to stop by, check it out, and go back to the resort when we were ready to leave.
CN is more compact - the restaurants are all in the middle of the resort, along with their amazing pool. CSA is more spread out, but flat and very easily walkable (and doesn't seem like you're walking forever and ever either). CSA's pool isn't as stellar as CN, but they have 2 to choose from at CSA, one with a swim up bar. We typically hang out around the pool and it isn't a deal breaker for us.
We also LOVE the gym and spa at CSA -- it's really amazing! Also, we felt like there are more healthy food options at CSA compared to CN.
It's not that we wouldn't return to CN -- we will at some point -- but we haven't had our fill of CSA yet so that's why we're returning there. In 2 trips we don't feel like we've done everything we can there.
My SIL will be at CSA on her honeymoon while you're getting married! I'm so excited for her to experience it. Good luck!
Melea & Joseph
CN - '06, '07, '08
CSS and CSA - '09
CSA - '10