Just back from 4 days at Nottens (Sabi Sabi) and cannot recommend them enough. They have a wide traversing area, sightings of all types were plentiful and never crowded - all sightings are limited to 3 vehicles but we saw plenty of sights with no other vehicle for miles around. Guides were superb and the lodge, food, pool etc were all first class.
Access from Skukuza is very easy (30m drive) and Airlink service from JNB both good value and reliable.
Would definitely do again.