Whenever my fiancee travels with me (for whatever reason, we're almost never on the same PNR...go figure), I call up and ask real nicely if they can seat her in a specific seat that I know is empty. Most of the CSRs that entertain my request put me on hold to ask their manager for permission to seat a non-elite in E+.

stbmurray, I've been successful doing this on both domestic and international itineraries where I'm a paying customer and my fiancee is either paying or on a free ticket of some sort. Most of the time, they don't have a problem putting her next to me in a middle seat. Sometimes if the stars are in alignment, I can get her a window and myself an aisle in 3+3 configuration aircraft and pray that my status can ward off a pax in the middle seat.