We're going with Couples San Souci for our weddingmoon. We looked at Sandals but there were a couple reasons we decided on Couples.
1. The Couples Message Board-great place to get info from people that have been there, some of them many times.
2. The inclusions-CSS seemed to have a wider range of included activities.
3. The CSS property is a quieter resort. We're don't want to be around a lot of people for the wedding/honeymoon. If we were on vacation it might be different.
4. Couples has some great specials. We got in on a $350 Spa Credit and $150 Gift Shop Credit when we booked.
5. We could get an upgraded room at Couples for the same price as the basic room at Sandals.
So, good luck deciding :-)