The trio of countries, Kenya - Tanzania - Uganda, are high on the itinerary of travelers seeking high-quality safaris in the real wild Africa.
Each of the three countries requires Canadians and all other westerners to have a visa prior to arrival.
The good news is that travel between the countries in this group is rather easy in terms of visas. You can now use a single entry visa (issued for each country to which you will travel), and then re-enter the first country using your single entry visa.
This means you can land in Kenya, visit Tanzania and Uganda, and return to Kenya on your single entry visa. This also means you can land in Tanzania, visit Kenya and Uganda, and return to Tanzania on your single entry visa. This works for re-entry to both Kenya and Tanzania, but not for Uganda. Uganda will sell a second visa at the time of re-entry for US$50.
So get your single entry visas and go on safari in Africa!