Costa Vida is my go-to restaurant for when I'm busy and need something yummy and decently healthy. That healthy part doesn't go for all of their dishes, but fits the vegetarian salad I always get there (I get no tortilla and swap in fajita peppers, plus everything else that comes with it). I really stay away from fast food, but that meal from Costa Vida is my big exception.
Their tres leches cake is also SO good, if you love rich, sweet things and want to indulge.