Based on this, I just switched from front to the back so I'd have better chance of having middle seat vacant for a 3 1/2 hours flight tomorrow. Let's hope there wont' be too many nonrevs on this flight.

Normally, I like seating near the front of economy, but if agents won't take into consideration the fact that FFers tend to be up front in economy when assigning seats, as well as letting anyone pick seats anywhere, then I may as well as sit further back and hope for the best.

Thanks everyone for confirming my theory.