I am finalizing a RTW booking routing JNB-HKG-SFO-LAX-FRA-JNB for a trip in July.

I managed to find availibality on the following carriers and flights:

JNB-HKG: TG (via BKK), no D seats on SA or SQ
HKG-SFO: UA on 744 or SQ on 773 (worth it to pay the $500 charge on SQ?)
SFO-LAX: UA upgraded to F
LAX-FRA: LH on 744/346 or UA
FRA-JNB: SA via MUC or LX via ZRH

Please comment on the coices available as I normally only use SA/EK/LX for business travel.

As this will only be a 10 day trip I would only want to travel in C, can I upgrade a Y RTW booking or would it be better to book the C RTW fare.

Thanks