There is no universal answer to your question. It depends on your travel plans for 2012 and what different benefits are worth to you -- the subject can be debated endlessly and has
http://www.flyertalk.com/forum/unite...-11-posts.html
http://www.flyertalk.com/forum/unite...-platinum.html
and somewhat related
http://www.flyertalk.com/forum/unite...ad-merged.html