It's important to do some preliminary research beforehand to determine your must sees, but it's just as imperative to leave some wiggle room for the unexpected. Unforeseen hiccups will inevitably arise (that's life, my friends), and if you have your days planned from sunrise to midnight, you might be left disappointed — or worse! As Phil Santoro, cofounder of VacationRenter, told us, overstacking your itinerary would put you in a sticky situation: "Leaving wiggle room in the agenda is ideal to avoid being so booked that you risk missing your flight or a prepaid activity because something else is running behind schedule."