looks like it's going to work. all in business class:

clt-muc (lh)
muc-ist (tk)
---stop----
ist-jnb (tk)
jnb-mru (sa)
---dest----
mru-jnb (sa)
jnb-nbo (sa)
nbo-cai (ms)
---stop----
cai-muc (ms)
muc-bos (lh)
bos-clt (us)

fwiw, your advice against ms made me change the ist-jnb leg to tk.

i also read that ms does not serve any alcohol on board (gasp!), but that you can bring your own alcohol and they'll "provide mixers". hilarious!

looking forward to the trip (march 2010)!!

thanks again for your help, everyone!