Perhaps something wasn't clear in my previous post. I wouldn't necessarily use all the miles by August 2001, but I'd have at least one more Delta flight so they wouldn't expire. This makes the expiration-extension value of flying Delta this year trivial. (As opposed to some other programs, Delta miles don't expire unless you have zero DL flight miles for 36 months.)

To respond to BlondeBomber's question: Delta "select fares" exclude deep-discount "L" fares. In my limited experience, upgradeable Delta fares cost more than the cheapest AA fare PLUS the cost of AA 500-mile upgrade "stickers," especially at the elite bulk rate of 8 for $200.(There's more on this topic, including not a little frustration, in the Delta forums.) That was one reason, though not the only one, for my switch.

Good point, though. I'd probably spend more time in front in AA than in DL.