I just returned a few weeks ago from a wonderful vacation in Aruba. This was my first time there, and I was pleasantly surprised with how knowledgable people on the island were about gluten free and Celiac Disease. Everyone speaks English, and they know their foods well. I felt very safe eating there. I stayed with some friends in my time share at this Marriott Vacation Club resort. There are three other properties owned by Marriott -- all in a row on the same boulevard: Marriott's Ocean Club, Marriott's Resort and Stellaris Casino, and the Ritz Carlton. We ate at many of their restaurants, and I didn't have a problem anywhere. The Seaworthy's Pool Bar at the Surf Club was great for snacks, breakfast, lunch, or a light dinner. The women who waited on us all understood what gluten free meant. I could eat almost everything at the breakfast buffet, and we also got chips (GF) and salsa for snacks. They even will deliver food to the beach if you like. The Marketplace grocery store on site did not have many gluten free items (but we went to a Superfoods market nearby that had quite a good assortment of gluten free items in a section of the store -- many that you would find in the U.S., including gluten free pasta and crackers.
At the Marriott Resort and Stellaris Casino next door we dined at Simply Fish -- by candlelight on the beach. It's moderately expensive. I ordered branzino, a Mediterranean fish I'd never had before and loved (sometimes it's called European sea bass). There were probably only about two dishes on the entire menu that I couldn't have, but they probably could have modified them if I'd asked. Our waiter was very informed. We also dined at Ketsu Sushi Bar at this resort two times.
I want to note that the restaurants here are not Marriott owned and operated restaurants, but you can charge meals there to your room, which is convenient. There's also a Ruth's Chris Steakhouse in the hotel, and they are known for being very gluten-free friendly.
I'd recommend any of these Marriott properties (you don't have to have a time-share there) to anyone who is gluten free and looking for a relaxing and wonderful vacation with plenty of safe places to dine.