One option might be:
Seven Seas Navigator
From her all-suite accommodations (90% with balconies), to her signature cuisine, the 490
Mumbai (Bombay) to Cape Town
on Seven Seas Navigator
20 Nights
Departs November 01, 2008
http://www.rssc.com/voyage/search.do...®ion=AFRICA
Silversea and Seabourn have African cruises. Silversea's shortest is 7 day but most are more like 11 days.