A lot of the reading I've done indicates that the US dollar is widely accepted, and even mentioned the ranger tips. We are thinking of getting a small amount of Rand in the Atlanta airport; I assume there will be a kiosk there. I've been trying to figure out whether or not we will need access to an ATM card because my small bank is totally backward in that way and allows a maximum of $600 per day (only $600 for Fri-Sun weekend total).
I can take a different card, but Mark strokes out when I mention the only other one we have (he really doesn't believe in them).

He plans to take about $1500 US cash, I think, and he assumes I'll have some with me, too.