MAD-FCO-ADD-JNB-ADD-MLA-MAD (
12073 miles)
€394 / $430 with Ethiopian
Looks to book into T-class, which
earns 50% actual miles flown with UA, for an admittedly not great 7.1 CPM.
Still may be helpful for someone interested in a safari who can get to Spain. Also available in mid-$500s around New Years.
Example:
https://goo.gl/flights/IFCO