We just got back from CSS last Wed. You can go over to SSB anytime you like, however, the only time it is truly AN is 9am to 5pm. If you go over late at night there will usually be other couples. How many just depends. A guard is also usually roaming the grounds, he is there for your security not to gawk. The above post is correct it is dark over on that side. You will enjoy the night atmosphere, it is very romantic.
"Once you go...you know"
We're there right now. We've all been having a great time and staying after 5:00. Usually til about 6. Last night, we had a few younger folks come over to the pool and try it for the first time after 5:00 (sunset viewers, with no sunset because of clouds). They may come back today and try it on the beach under the palapas (more seclusion). Remarkable, amazing and fun to be part of.
We Miss SSB... Our next trip is to CN August 2011. I doubt that the AN beach there can even slightly compare to SSB. Oh well, this will complete our Grand Slam and then we will have beet to and know all the resorts. So far CSA (even without AN) is our favorite with CSS a very close second.
We were there back in June. Sometime people stay on after 5, and when the 'other folks' come over for the sunset viewing they tend to sit on the beach, the AN folks stay in the pool. No problem, man. I was amused though by one couple who sat together on the beach, theoretically to view the sunset (which doesn't happen at 5 in June) but sat with the necks permanently twisted at 90 degrees. (Honey, do those folks have clothes on? I don't know dear, let me check.)