IMO there's merit in being pragmatic rather than jumping at what appears to be the biggest bargain. Why add a continent (Africa) to your itinerary if you have no real urge to go there? I like your approach, simon50: decide what you really want out of the trip and see what else you can get for very little effort and cost.

On my first RTW (sort of) I needed to get to the UK and Australia from South Africa. The AONEWC3 (Circle Indian Ocean) fare was way cheaper than direct fares in J. In addition I could get them for much less in HRE, without too much fuss. So I got an amazing deal and as a bonus the trip propelled me to Emerald status. The fact that I utilised only 2 sectors in Europe (and those in BA's execrable "domestic business") and none in Asia mattered not a jot. Any more travelling on that trip (13 flights in 2 weeks as it was) would have just been unnecessarily exhausting and pretty pointless.

Of course now that I've done a few, I'm getting into that stage of blue-sky planning where I start with no, or few, fixed ideas of what I have to do and construct a trip that is much more driven by incidentals like where can I fly in F on xx airline or how to retain status on several alliances. Plus I have gradually introduced SO to the concept of the MR and the benefits of status, so I have more leeway for such indulgences.