I remember there was a thread in the AF forum recently where someone provided a list of AF those destinations that are served in First. Maybe you can find a similar thread in the KE forum. (If not, you could always try to book a First flight on some website for a destination you are interested in.)
As far as I remember, the AF flights with a First cabin were into some US cities (such as LAX and NYC), maybe also one Canadian airport, some South American aiports (think EZE, for example), some busy Asian destinations such as TYO and HKG, African destinations such as JNB and maybe some dictator-run oil producing country, and (I hope I remember it correctly) DBX and maybe even Cairo. (But please look it up in the thread for yourself. I just wanted to give you an idea of what to expect.)
Generally speaking, the number of ST First Class destinations is not very large and mostly includes transcontinental long-haul flight. So you will probably not be able to have more than 3 to 4 First class fights on your trip. (e.g. Europe - The Americas, US - Asia, Asia - Europe, and maybe Europe - South Africa). And this is perhaps an explanation of why the fare difference between Business and First RTW tickets is not very large.