Marc,
June and i are booked on the MIA to BA segments for 2018.
Not sure if we would do Machu Pichu. I have been but June has not and we currently are on the MIA to LIM segment. For those who have not done Machu Pichu I could not recommend doing that more. Would think something Ngaire arranges much better than Regent tour. The altitude can be an issue for us older folks but that is not a problem for you younger ones.
Would do the Iguacu Falls for sure as a post cruise event.