Do they need to eat completely gluten-free, or do they just avoid it, for preference? My buddy with celiac disease who really needs to not consume any (so, yes, to the PP's point about how soysauce often contains it. Similarly, many restaurants will steam veggies in pasta water, which will make someone with celiac disease feel sick.) says that chain restaurants are, alas, often the best about having a really gluten-free menu. Austin grill over by Penn Quarter is good. Jaleo can do it. So can the generic shopping mall restaurants like olive garden and mccormick and schmicks. I'm not sure about their fish offerings, but Nando's has gluten free options. Cava Mezze does. And there's a pizza place at Pentagon Row that does and might be good for veggie options.