Hi parrothead. Our family's personal favorite beach is Chankanaab Park. Great snorkeling. Clean, beautiful beach. Wait staff walk around the beach serving a variety of fancy drinks. Food is also available at the Park. You may also purchase souveniors here, as well. There are lounge chairs on the beach for your use. We bring the towels from our cabin. The Park is lush with tropical growth and Iguanas are roaming around. The Park will be closed if there are high winds.
As for jeans in the dining room, people were wearing them last month on Pride. One gentleman had on a very dark rinsed "dress" jean with a nicely tailored shirt. He looked very nice. I would not wear ripped jeans. But, I believe, other than formal night and if the jeans are presentable, you're okay.