If you are trying to plan for a late arrival, look more closely at your touring plan. I have found that if my plan is so tight that I am worried about arrival times for meal, it is too tight, and that is a stressful vacation. I don't arrive late for ADR's but I have been wicked close and it was not a pleasant experience. The one time we were late, we had a meltdown with one of the kids and the concierge called to let the restaurant know. They accomodated us as a courtesy, but we were waiting a long time before they could seat us. I would never do this a part of my plan for the day becuase we ate, but it was late, and I am not at all sure we would have been seated if not for that call from the concierge. This was in August and was a FD period. The restaurants were booked solid.