Not knowing what park you will be at on your last day is key. That, and I am not sure if you are talking about your last full day or your last day but you will have a flight out at 7PM or something.
Unfortunately, not knowing hurts you... you have a few options I think.
With Park Hoppers:
1. You could make a breakfast ADR before park opening at a Disney park... which ever one, then go to your favorites from there.
2. You could opt for a late dinner ADR. If you aren't flying or driving out on the day in question, having a late night ADR is ok since you'll just be packing and sleeping on the plane/car anyway... minus he/she who is driving.
Without Park Hoppers:
1. Make an ADR at one of the many TS restaurants in a resort hotel. Again, either early or late so you don't ruin your day or waste time eating when you have a lot of favorites to attend to.