Delta regularly runs an auction for various experiences including sim time in Atlanta. The last I looked at it it went pretty cheap - like 70,000 miles including domestic travel. It wasn't on the last auction.

http://www.delta.com/skymiles/sm_pro...tion/index.jsp

I did however finagle my way into a couple of hours of UA 747-400 sim time in Denver a few years back. Ranks in the top 10 of my great life experiences. Toughest landing was the approach into the old Kai Tak airport. What a ride!