Was there in 2017 in a car, did not attempt to rent a plane (never occurred to me to do so, not sure it would've been super scenic to be honest)
Some notes:
It's quite chilled, but they have the same severe income disparity you'll find all across the continent, so crimes of opportunity abound. Be guarded, don't wear 'bling', don't flash cash and expensive phones (all the usual admonitions, yadda yadda -- I assume you don't need them). We made a point of not walking around at night, but that was probably not necessary.
Like ZA, Car liability insurance is included in the price of fuel. Nam's scheme is a bit complicated and has big gaps in coverage. I'd get extra cover if you can swing it. Petrol stations are all attended (like Oregon and NJ), and a ~$0.50-ish tip to the attendant ($20 NAM does the trick) is expected AND appreciated..
Namibia's German colonization roots means the people aren't as friendly and outgoing as, say, Zam or ZA. Teutonic Africans took us a bit to adjust to.
I'm sure Swakopmund and Etosha are on your list, if not, add em. In addition to self-driving Etosha, we stayed at a private game lodge nearby which cooked up all sorts of barbecued beasties -- we ate Guinea Fowl (yuck), Ostrich (btdt, meh), Oryx, and Kudu (super yum), in addition to the usual treats on offer. Don't look for exotic salads, it's meat central down there.
Windhoek is a neat place to explore, but you can be completely done with it in 2 days.
The dunes of the Namib didn't do much for us, but we had already been through the Sahara at that point.
If you've ever driven from, say, Los Angeles to Las Vegas, on a random Tuesday morning -- the distances and lack of 'things' is about the same in greater Namibia. Unlike I-15, you'll only see about 10 other cars on the road each hour.
Google Fi did *not* work in Namibia for us, neither did T-Mobile -- we had to get an MTC Sim card for my dual-sim phone. It's not a simple retail process, it involves registration of your passport with some central bureaucratic machinery. Plan an hour or two if you can't get it beforehand. Data is expensive there. (~$10/gb)
$0.02. I'd love to hear how the flying goes.
(Apologies if you only wanted anecdotes about General Aviation there, I got nuffin)
