Yes, as a Silver member, we snagged a cabana twice. The first time was truly a HUGE luck of the draw. Just happened upon an opening one morning on the internet and voila! we got it. The second time we were on a Facebook page for our cruise dates and someone posted they were canceling their cabana. I was on that website lickety-split before someone else saw the post.
The first time we had the cabana we split the costs with 10 people. We were never there together all at once though. We honored the 6 person rule (that only up to 6 people in the cabana at a time). Many of the people were on excursions--snorkeling, the 5K run, and bike ride. Worked out for us that cruise.
The second time we had the cabana I broke my ankle just 5 days before the cruise, so my great adventure was the cabana where I could be sheltered and still on the beach. It was truly a blessing that day.