I spent a few days in Cape Town and a couple in Victoria Falls back in '97, so my opinion is by no means an expert one. The game viewing around Victoria Falls was pretty limited. Nothing like what we saw in Kenya later on the same trip. We stayed at the Victoria Falls hotel, which was quite nice, except for the bullfrogs in the courtyard keeping us up at night!

Since your time is limited, I'd think about passing on Victoria Falls. The falls are quite impressive, but you would be eating up a good amount of travel time to get there. That's time you could spend game-viewing in SA or Botswana instead.