We had a welcome dinner at one of the buffet restaurants (if you want an a-la-carte restaurant, you'll have to have a set menu for over 10 guests... which we didn't want). Rocio reserved a section of the restaurant for us, which was nice. No extra charge. I'm assuming you could do it for a brunch as well.
For our rehearsal dinner, since there was once again more than 10 people and we didn't want to force a set menu on everyone, we had it at the Beach BBQ. It just so happened that the BBQ was the evening before the wedding, and worked out perfect since we did a quick run-through rehearsal before heading to the BBQ. The food was good too... BUT, it was extremely windy and we couldn't wait to get out of there. It's hit or miss... the BBQ that was 2 days later was better, now wind.
We only went to Coco Bongo's in Playa del Carmen. We had a bunch of guests that went to Delphinus to swim with the dolphins... some went to visit the ruins... other went on various excursions. There is something for everyone