I know this comment will be unpopular with Silvers and non-elites, but I am delighted that only Plats and Golds can pre reserve Exit Seats.
On my upcoming trip to SJC this weekend, I had ZERO difficulty booking exit row seats. Wide open. If CO wants to keep me as Platinum (I am deciding between UA 1K and CO Plat for 2008), this would be one of the major reasons I would stay. We all know how abysmal CO non exit coach is. If Silvers can prebook, then the chances of a seat open for me will be much reduced (as there are many many Silvers--one trip to Asia on a H fare or more puts you almost at Silver).