...and my last visit was 40 years ago !
I don't know how old you are, but white water rafting is pretty fun if you can manage it. The climb out of the gorge is pretty tough unless you are at least moderately fit.
It is not technically necessary to get Yellow Fever shots for Zim, but, the border guards have been known to try their luck at soliciting a bribe with the threat that you will have to have the shiot right there and then.. they went so far as to show my friend their not-even-slightly sterile equipment. This was at the Beitbridge/Messina crossing through.
Take dollars, take as many small currency notes as you can get. The cheapest thing in zim is US$1 - and you are unlikely to get change if prices do not round to a full dollar.
Before your way out, spend ALL the dirty, old US$ notes that you will accumulate - they cannot be exchanged in this country due to their age and state.. you'll see what I mean.
A booze cruise above the falls is pretty nice for sunset, and (although I have not done this) a trip to Zambia is apparently worthwhile for a more vibrant economy, better food and a different view of the falls.