Since last year, I have been splitting most of my flying between Delta (which previously got nearly all my business) and United. This year, based on actual flights taken and those already planned, I will finish with roughly 120,000 Delta miles and 87,000 United miles (status miles, of course). Obviously, I wish that I had done my splitting a little more precisely! In November, I'm flying Delta to San Francisco, but I have no choice in that case (corporate discount).
I'm still pondering whether or not it's worthwhile to squeeze in another 13,000 United miles this year (if I can find the time). I like United a lot, but 1K status seems to be worth much less now than it used to be.
Bruce