While I have not been to CSA, I had been to CN three times and decided to try CSS this past September.I was hesitant as I just love Negril. My advice is that if CSS appeals to you... GO! CSS is amazing, beautiful, romantic,and simply fantastic. The staff and service were top notch. It is so different from Negril but so wonderful. I did not think I could find a resort that I loved as much as CN but now I love CSS just as much!! Enjoy!
Here's a quick description of CSS: the newest to the Couples resort, but not the newest built. It used to be a Grand Lido then Couples bought it. The beach is smaller than those in Negril but it's completely private. Separate beach for nude sunbathing. Resort is spread out and built on cliffs. It's split into 3 different levels, lots of steps throughout. Lots of foliage and hidden spots. Does not offer a catamaran cruise. 3 restaurants but full menu room service. All rooms are suites with mini bars. Rooms are more hotel like as far as the decor.
The only way to really know if you'll like CSS is to try it out. The one piece of advice I can give you if you try CSS, as someone who has been to them all, don't expect it to be like CSA at all. They are both fantastic, but they are both very unique. Of course, that goes for all of the Couples. We tried CTI first, then CN, then CSS, then CSA. If you expect any of them to be like another, you could be disappointed.