If you are doing pre-days I would do the abd hotel as you then get the transportation which is key in arriving in Lima. I would say not as much for the post stay. We took it easy our pre day and visited the pyramid. I've also heard good things about the light show. As most flights arrive at 11 or 12 pm I recommend a pre day.
We booked our trip a couple of weeks ago and added an extra night on the front as our flight gets in late at night. If you do the add on through Disney they will still pick you up at the airport.