We took a courier taxi from Pretoria up to the Tswaing Crater site. While the driver was unsure if he could get into the site as a trael courier, there was no problem in the end, and he even got out and walked to the rim with us (a first he claimed).
The Gene Shoemaker memorial viewing site was appropriate, but was well hidden. But the views from here were fantastic. Really giving you a sense of awe of the impact that made the crater, and so unspoiled despite having been used as a salt pan for many years.
A safe walk to the rim from the visitor centre even for us 'older' unfit couples.