I've been going to southern Africa in May - June to avoid the heat and mossies (therefore we don't take malaria meds).

I HATE that Gate 1 itinerary - so much driving, not staying inside the parks, doing too much in too little time. For $4000 (plus optional tours), you can do better on your own. No need to go on a tour - private transfers are affordable. And it's really easy and safe in those places. And the accommodations on that tour are not so great. My mother, in her late 70's, thought a tour would be the best option for a first trip to Africa, too. She is so happy to have been on a personalized tour. It was arranged without any hiccups or problems.

I would arrange a trip to go to:
Cape Town 3-5 nights with private day tours to wine country and Cape of Good Hope, the rest you can do on your own or not (Robben Island, Kirstenboch Gardens, Table Mt, etc)
Vic Falls 1-2 nights, depending on arrival time, arrange for a tour, boat ride, bungee jumping?
Chobe 3 nights
An affordable camp in Sabi Sands (or Timbavati), a private game reserve in greater Kruger 3-5 nights

With layovers in Johanessburg, it's the same length of time. Save Swaziland and Hluhluwe (which are both worthy of more time!) for next time. while in safari camps, everything is taken care of - they will love it.

Thank you, Christabr, for your reply. Very helpful! I looked at some of the other tours, but none give all three countries. Besides going the private company route, do you know of other tour companies that have a less harried itinerary? I had opted to go for an escorted tour so that the two Moms would be able to get company (other than their own) - they do get along, but I thought if they have a group of people, it may be better (2 weeks of togetherness may be too much!!) .

The only time they will be "together alone" would be in CT and VF. At almost all safari camps, you eat communally and the game drives are in a group. It's my favorite part of safari - meeting people from all over the world. Really - private tour is the way to go! Every affordable tour stays in crappy places and moves around too much.

You can also arrange group tours in CT and VF.

Ntaba Tours in Kentucky is owned by two South Africans and they have scheduled tours or can book a private tour for you. They do have a scheduled tour in October/November, but it will be hot then. Their tours usually cover the areas you're interested in. Ask for a full price including air transfers, as their quoted prices don't include those and that can add up.

If you think they would be more comfortable with a packaged tour, I suggest you check out OAT's African adventures -- specifically http://www.oattravel.com/Trips/2012/Ultimate-Africa-Botswana-Zambia-Zimbabwe-Safari-2012.aspx

We were set to go on this trip about 3 years ago, when we had to cancel out at the last minute because of a family medical emergency. (We had gotten trip insurance and there was NO problem in being reimbursed for everything we had spent.) While we have always been independent travelers, we were impressed with OAT. We were pleased with everything they did for us in planning for the trip (as well as their understanding when we had to cancel). My only problem with that trip, was that we weren't able to extend our stay in order to visit friends in Cape Town at the conclusion.

Now, everything is fine and we have planned an independent trip back to Africa this fall, and adding time on to our 10 safari in order to spend an additional 10 days (self-planned) in South Africa.

BUT, I would highly recommend the OAT trip for your Mom & MIL. The tour size is small enough to be manageable and large enough so that one doesn't have to feel they are stuck with the same people the whole time. Plus, it looks to me, as if unless someone is flush with air miles to pay for airfare, OAT is getting about as good a deal on international flights as you can find yourself.

March would be the best. March and April are generally nice months in Southern Africa, but Mei-July might be even better in terms of game viewing.

A friend and I have been comparing Smartours with Gate 1. Smartours with the Vic Falls extension is about the same itinerary as Gate 1's tour but Smartours gives you a lot more for the money. A few Fodorites have posted reviews on this particular tour if you are interested.

Smartours and Gate 1 are partners

How are they partners? They each have their own web site offering similar tours. They seem more like competitors to me.