As others have said, the dress codes are pretty lax and no reason to feel like you need to go back to the hotel or even carry extra clothes. Just wear a sundress, trust me, I wear them all the time and have no problems and no I don't wear shorts under them. Have your boyfriend wear a light weight cotton shirt or a moisture wicking shirt, some of those look pretty nice. Take some wipes in your bag and freshen up in the bathroom. You will be fine. We ate at Flying Fish last trip and the table across from us had a family with 3 kids. Mom had on running shorts and a tank top, Dad had on shorts and a tshirt, kids had on whatever kids wear (and were very noisy and badly behaved I might add). My son and I had gone back to the room to swim so we had a shower and changed clothes but we have eaten at the signatures in whatever we wore in the parks. We also did the dine in the sky thingy (can't remember the name) and wore what we had on in the parks. I had on capris and a cotton shirt, he had on khakis and a cotton shirt, we had worn them all day at the park. Mind you, it was in March so it wasn't so hot but still, it was what we wore to the parks.