I have stayed at the Hilton and as a gold they treated me well. Nice enough hotel, good breakfast. But have no idea if Sandton is close to where you need to be (Sandton seems a bit away from everywhere), so I can't help there.

I would strongly suggest if you can spare 2 or 3 days to try to go to Krueger and have a very quick safari. It is about a 4 hour drive (A driver can also be arranged) and if you leave early one morning, you can be there by afternoon drive, stay the night and have an early morning game drive and then head back to J'burg. It a bit of a rush, but is so worth it. It will really make you feel like you have been to Africa (and not just on another business trip). Just MHO.

If you stay in JBN, then be sure to hire a local guide to show you around for at least 1/2 day (the Hilton arrange for a wonderful guide for us, much better than any group tour).

Hope you have a great trip.