Hello, EVAN!. In response to your inquiry, I don't fly a great amount these days but I usually strive to get SM status with DL, mostly for the domestic flight perks like seating, boarding and shorter ticket lines. I am SM now and shortly will be GM until early 2010 by virtue of several recent flights that I normally would not have taken but needed to take because of family emergencies. I have a very large number of DL miles that I may never use up given my reduced amount of flying, mostly for vacation trips.
So, my thinking is that if I can get SM status or better by just waiting until the second half of the year next year and finding a bonus offer, why not accrue miles on other airlines during the first half of the year? (Assuming I would not have a "soft landing" next year with DL and only be demoted to SM for 2010 and beyond. I have to believe that soft landings will soon be a thing of the past given recent DL "enhancements".) I have lots of miles on other airlines from business flying over the years but no status with any but DL, mainly because DL offers the most options from my city. But status is not so important on those other airlines since I use those miles to fly on business class award tickets for vacations overseas (where seats, service or destination availability is better than on DL) and therefore have no need for status since I'll have the business class perks built-in. Still, it never hurts to add to those caches of miles whenever possible to keep the totals up for later use.
You point out that these DL bonus offers may not be there for me in a given year but it has been the case in recent years that they have always popped up in one form or another and could have been relevant to me if I so chose. To an extent I am speculating on historical data but that seems reasonable to me.
Thanks for commenting on my thought process. Never hurts to reconsider possibilities and choices based on the perspectives of others. I've changed a lot of my thinking based on the input of FTers. In the end, I'll probably fly DL the first half of the year next year just as I always do since there is no guarantee of late season offers but, as you suggested, sometimes it just helps to vent a bit.