I was there for the entire month of December in 2009 and it was unusually hot for longer than they're used to. My friends were complaining and I was like aren't you from here? LOL! I agree that 3 days may not be enough. Etosha is probably your best bet to see animals with all of the water holes there. I was a bridesmaid in my friend's wedding and her brother in law used to be a tour guide. He has his private and commercial pilot licenses and is in the works to start his own tour company so we did a test run. I had a wonderful time and I think I did pretty well for my first time in Namibia.

Where I went that may be of interest:

Safari
Brandberg
Palmwag
Epupa Falls
Etosha Pan
and everywhere in between

Swakop
Walvis Bay

Let me know if I can answer any questions.

There is that resort that has just a bed in the middle of nothing. I cannot remember the name right now, but I know it is very popular.