All - I am looking to using Amex points to book business class travel to/from JNB from NYC area this coming July.

I am most familiar with AA's frequent flyer program whereby you can always book flights, it simply requires more miles if the designated free seats are already taken. Do other airlines have similar programs? Options that I have found include Virgin, BA, South African, etc. My thought would be to convert Amex points to miles with one of these airlines or even convert them to Delta, Continental, etc. and then convert these miles to a partner airline like Virgin.

Does anyone have any experience in this area? The designated award seats on many of my options have already been secured. Thanks