I loved exploring the Kalahari Desert and only have great memories of my time there! Most of the time I crossed immense desert plains and, once in a while, would come across a cheetah, an antelope, a lion... The colours are amazing! Red, white, or grey sand and the only trees that grow in these arid lands - acacias and kokerbooms, the latter being weird trees that the local bushmen use to make their hunting bows. Take the time to visit one of their villages, which are part of the country's sustainable tourist drive and fascinating to see.
For me, the most impressive part was the cross-border Kgalagadi Transfrontier National Park. I started out in South Africa and ended up in Botswana. Entry formalities are dealt with at the park's entrance, next to the base camp. That very morning three cheetah crossed the road right in front of my car. My window was down and, to be honest, I got scared when one of them got up close to have a look. In all fairness, all he wanted to do was cross the road and have a drink. We slept in a bush camp on the border and the following morning spotted lions as we headed into Botswana!
Another highlight was our trip to the Central Kalahari Game Reserve, a sprawling landscape that stretches over 50,000km2! It was, without a shadow of a doubt, the biggest game park I've visited. It's breathtaking with a varied landscape, which is probably why the park was established in this region. The best bits were Deception Valley and the Khutse Game Reserve (further away, but worth the effort !).
To be honest is was a tiring trip, not least because of the heat and the time it took (7 days). If you only want to spend 2 or 3 days in the Kalahari, then you're better off leaving from Maun and exploring the northern area, where the lands are greener and the wildlife abundant.