The Caribbean - Punta Cana

Hi, we are going to Punta Cana in about six weeks, and we will be staying at the Riu Naiboa. Has anyone in here ever stayed there before? If so, do the restaurants have some sort of dress code for men at dinner time?

I haven't stayed at that resort, but based on where I was, you may want to bring at least one pair of long pants and closed shoes. That was the dress code for men at a couple of the "a la carte" restaurants. (The shoe thing is a bit discriminatory, I suppose, since the ladies can wear sandals, but not that much, since sneakers passed.)
Shorts and sandals were fine at the buffets and other a la cartes, so someone who hadn't brought pants or shoes would still have several dining options. Just not the fancier ones.