For a Oneworld Global Explorer, the DONE4 is a business class four continent round the world product. Your continents would be Europe, Asia, South Pacific and North America. It's hard to include Africa because there aren't many flights without an African carrier in the alliance.

You could save money if you purchase a DONE4 ticket and start in Cape Town. You can then choose to end your travels in Tanzania and make your way home from there. That is what I am doing.

For a sample 16 segment itinerary that is valid from London: LHR-DME-AMM-DXB-BOM-HKG-NRT-PEK-PVG-MEL-AKL-LAX-DFW-YVR-MIA-JFK-LHR.

That is London to Moscow, to Amman, to Dubai, to Mumbai, to Hong Kong, to Tokyo, to Beijing, to Shanghai, to Melbourne, to Auckland, to Los Angeles, Dallas, to Vancouver, to Miami, to New York, to London.

Do St Petersburg on seperate ticket.
See Petra and Wadi Rum while in Jordan.

Internal Australian flights are cheap at the moment with three budget carriers. Suggest you fly to Melbourne (my home), cheap flight to Adelaide, train to Alice Springs, fly to Cairns, tour down the coast all the way back to Sydney via Whitsundays, Fraser Island, Gold Coast, Byron Bay then back to Melbourne to continue your RTW.

I think you need to get a circle pacific or some kind of other pass to visit pacific islands, it's more Air NZ thing than Qantas, and that's star alliance or check out the Air NZ or Virgin Blue website.