I've felt the same way. Flew DL once in 2006 and then quite a bit in late 2007 and 2008. It's not perfect, but I find it better than AA, especially in Y. Considering much of my flying is RDU-LGA on RJs, I actually prefer DL b/c their CRJs are more comfortable than AA's ERJs (I know that shouldn't generally be true, but I find their CRJs quite nice). DL actually offers a snack and my experience with FAs has been better than with AA's.
In fact, I may get gold status this year with AA (due only to the double EQMs), but if not, I don't care. I just take whatever is most convenient now (my schedule has become very rigid) and after that, whatever is cheapest. B/c so much of my flying is RJs, elite status doesn't get me so much any more (I don't really care about the bonus miles).
Also, while redemption rates are truly terrible on DL, one thing worth remembering is that getting SkyMiles is really, really easy. Essentially, what has happened is inflation. Lots and lots of miles chasing very few SkySaver seats; instead, people have to buy SkyChoice (double miles). However, their new 3-tiered system should mean you can do it for slightly less than double miles. While this sounds like a terrible devaluation, it really is not so bad if you consider that you can so easily get so many miles on DL. It's worst for people who fly to get their miles; for those who get them from CCs and purchases, Skymiles is a great program.