We did the private dinner on the beach and it was awesome. Well worth the price! Maybe not something you would want to do every trip, but we loved it.
It was after sunset and sand fleas were not an issue for us.
I took a spray bottle of Off with me and sprayed myself when we left our room in the evening for dinner. When we were done eating dinner we took a stroll around the beach in the evening everynight after dinner with our friends. I had no problems at all. I started to carry the small bottle in my pocket in the evening for our friends since they did not bring any. Some people get bit more than others. It's not that bad. As soon as the sun starts to set the small bugs come out.