I think at this stage you should start with where and when you want to travel, and see if anywhere works. How open is your window of Spring 2014.

There seems to be nothing available from TPA but some from ORL. Unfortunately that takes you to LGW; I expect most of the places you want to fly on to are from LHR. But the connection LGW-LHR is probably easier than SRQ to MIA?

Once you have some dates, try some separate onward bookings - you'll probably be out of luck for popular destinations like JNB. MCT is possible. DEL likely.

How about NBO - probably very out of favour right now but has very good availability. Don't know where you've been in Africa but we found hopping round Kenya in Cessna Caravans more thrilling than South Africa ... though at that time of year you might want to see how easily you can hop over the border to the Serengeti.