Those places are far. Not driveable practically speaking.
Yeah, according to gcmap.com, like 600-700 miles at least.

So... options currently on the table (a combination of all three, or only 1 or 2): Buenos Aires, Iguassu, Rio De Janerio.
1) What's the best way to travel between these places - Avios? Or something else?
2) Which of these places should I do, and - if more than one - in what order? Ideal time constraint is basically a week (Sun-Thurs), though we can try to do a weekend also if it really makes a difference.
3) I'll be attaching this to the tail end of a UA mileage ticket, so I'll be flying *A, either from NYC or CLE (nonstop strongly preferred). Which is the best airport to fly into, and (if different) which is the best airport to fly back from?
4) Should I be entertaining any other options?
TIA