Good luck on your search. Those beautiful ancient cities where built with aesthetics in mind not accessibility. Another thing to be cautious of whether the ship docks in port or weighs anchor and tenders you to shore. This might create additional difficulty for your wife.
A Bad Day At Sea [with power] Always Beats A Good Day At Work
Alaska 2014 - haven't picked a cruise yet
Carnival: Glory 2004, Destiny 2008, Splendor 2009, Freedom 2011, Valor 2012, Dream 2013
Celebrity: Summit 2011
Princess: Ruby 2010, Caribbean 2013