Try to eat local specialties and to dine in locally owned restaurants. You may have to resort to a McSomething or other, especially if you travel with children, but there's no point in going to Europe, Asia, Latin America or even to another part of the USA if you don't take advantage of the chance to dine on something different and special. For lunch, try a place that looks like a family-owned restaurant (even if it is named "Mom's"). For dinner, you may want something fancier, so ask your hotel front desk people what they think. (Ask someone who looks experienced, not the new teen-aged night clerk, of course.) You shouldn't go to America's northeast or the maritime provinces of Canada without eating lobster, or to Florida without trying stone crab. Eat authentically in Italy or France, even in Britain nowadays, and you'll long remember special treats.
Try to avoid your own fancy hotel except for breakfast, which may be hard to find outside. If you are traveling by car, there is no limitation on where you may go for all three meals. If you're careful and do a little planning ahead, you'll be able to say you never had a bad meal during your vacation.