Yes, there is a wooden walk way (with stairs) next to the falls that your wife could walk up and "watch you" climb. There are also several places along the climb where you can climb out of the falls and get onto the stairs if she want to try to go a little bit.
As far as the bob sled run... it is probably label as more strenuous because the road the sleds run on is not the smoothest. So there is a lot of jarring bumps ...
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007