Basically you have three choices
1. Lodges within Kruger National Park, run by SANParks themselves. These are located in Rest Camps within the Park (see www.sanparks.org for more info)
They are self-catering, with basic facilities but are well maintained and excellent value for money. there is a restaurant and/or shop in most Rest Camps. You would self-drive in a hire car to your chosen camp. Then self-drive whenever you wish during daylight hours. You can also book Guided game drives in most camps, where you would go out for around 2-3 hours in a camp vehicle with a guide
2. You could book accommodation just outside Kruger NP, in a guest-house/hotel in somewhere like Hazyview for example where you are a few km from several entry gates to the Park. Again you would self drive and/or arrange guided drives.
3. Private game reserves - Most are bordering on Kruger NP with a few having concessions within the Park. In a Private Game Reserve it would be in All Inclusive deal (usually). You would get excellent accommodation, all meals and two game drives per day. These would be taken in smallish open vehicles, usually 6-10 passengers per vehicle together with a ranger (who would drive) and a tracker, who is also an expert on spotting animals.
These can vary from very nice comfortable lodges to extremely luxurious places
The prices of course reflect the level of luxury. They can vary from around 2000Rands pppn up to 12000Rands pppn
Depends to a large extent on what you are looking for and of course your budget.
With accommodation in a Rest Camp and Self-driving within Kruger, you can not go off-road, therefore your animal sightings will depend on what animals are close to the road. Don't be too put-off by this conception, it is quite common for elephants/buffalo/giraffe/zebra etc etc to wander along or across the road. You will usually see plenty of smaller game like antelope/warthogs etc. We have regularly seen lions on or at the side of the road and have had leopard walk across in front of our car. So plenty of animals will "find you".
In a private reserve, the ranger, can, at his discretion, go off-road and get close up to good sightings. They keep in radio contact with fellow rangers so "good" sightings like leopard/lion/cheetah etc are soon reported around. In the reserve I usually visit great care is taken not to cause disturbance to the animals and no more than 2 vehicles at a time approach a sighting. Maybe only one at a time in the case of a leopard.
You certainly have expertise in these reserves and I cannot remember a visit when we haven't seen the Big-5 close up (and I mean from about 10 yards away or even closer if the animal itself chooses to approach closer)
We try and have a few days self-drive in Kruger NP and a few days in a private reserve so get the best of both worlds. We book everything ourselves rather than get involved in a tour party.
Hope this info helps you understand the options a little better.