Iguazu Falls - Both sides are amazing! Definitely do the boat ride to the foot of the Argentina side. And get a pano view of the falls from Brazil. make sure you get a visa first!...otherwise Carlos the taxi driver can take you across ;)
One of my favorite memories is having the opportunity to drive 15 minutes to Nairobi's National Park. A few times, we got to stay at a Tent Resort & were able to see wildlife, just like this photo.