Back to the drawing board

For a couple of months now I have been planning a trip to Africa in April/May. The plan was to go on an organised tour starting in Rwanda and ending in Kenya that would include going up to the Mountain Gorillas, famous from the Gorillas in the Mist film, into Uganda and end in Nairobi via the Masai Mara. It's been a struggle getting the friend I am travelling with to get his holidays agreed and we had finally got to the point where we could book the tour - only to find that the tour has been cancelled by the company due to the lack of demand.

So now, holidays are booked through work now just need to find somewhere else to go. There are 5 or 6 options. One is to do a similar trip round East Africa but not organised, there is trip from Zimbabwe to Johannesburg; trekking in the Himalayas; travel through Argentina and Brazil or tour Uzbekistan.

Are there any recommendations or alternatives any of you may have? Travel dates are 21 April to 11 May