You have been asking about Vietnam. Saigon is the business center, busy, noisy, crowded. Hanoi is government, still more the old communist mentality. Not a lot of things to do / see in the cities. Vietnam is good for traveling around. Halong, Hue, HoiAn, Nha trang etc. Nice beaches, countryside, good food. If you plan to spend only 2 or 3 days either Saigon (slight preference) or Hanoi can provide you with some first impression. If you stay longer then definitively travel around. Flights inside Vietnam are cheap, book on the Vietnam Airlines website to get the 'local' prices.

As said before your itinary is not really geared to the best First Class experience.You should try to maximize F sectors and good airlines.
If you did Tokyo as side trip from Hong Kong you could use QF Fto Australia.
CX has some flights with F to NRT, check if the JNB flight has F year around - not sure what the current status is.
Lan also has no F, you could go on QF to LAX, then AA to south America, and BA to Europe.
AA F sucks, it is not much better than LAN Business.

If you really want to fly in F (which with your original itinerary seems to be a bit of a waste) you should consider Star. More choices for F.
LH or LX Europe-South Africa, SQ to Asia, Australia. United (not much better than AA to the US and on to South America (or go back via SIN or NRT), LH or LX back to Europe.