Okay, fair enough. I get it now. Then let's talk about right now.
McCain has voted with the President:
95% of the time this year (while courting the crazy base vote)
77 of the time in 2005
67% of the time in 2001 (link above)
I cannot forgive McCain for scrambling to the Right (just as I cannot forgive Obama for doing the same), but I am not completely convinced McCain would continue to kowtow to them if in office. His record suggests he may be using them because he needs them. PERHAPS NOT. Regardless, combined with the fact that the Dems will control Congress, McCain's ability to govern from the far right will be greatly limited. I'm not saying McCain would be better than Obama (he wouldn't), but I'm not necessarily convinced of the premise that Neocons would be large and in charge based solely on McCain in the executive branch.
Also keep in mind the perceived pottery barn rule. If the economy continues to fall (which it may regardless of McCain or Obama's plans -- because it is that broken) the ownership of the "fall" will be laid at the feet of the ruling party. That might not be fair (depending on if the Reps or Dems are in office at the time), but that tends to be the way it is. So if the Democrats are elected in a tsunami and they can't fix this (and I honestly believe they might not be able to) there may be such a huge backlash against the party in 2012 that the Republicans are right back in. Voting for the Democrats now may due more to set back the party in the very next election. That might be too long term, but it is something to consider.
Yes, Obama would be better than McCain, but I believe "throwing my vote away" for Nader would be better than either. I agree with you when you say that pragmatism requires balancing long and short term goals, the problem is I don't think Obama leads us out of the pit in (enough of?) a meaningful way, so the only thing I can do is help position a candidate that will be able to get us out of this mess. When neither guy can get it done in the present, I can only try and setup an optimized future.