How much better is CLS for what I am interested in? Is the advantage of CLS--for appellate lit and elite PI--worth $120k?
This is a tough question to answer. The answer I would give you (again, if you can't tell by now, I'm biased, so take this as one perspective) is that Columbia is a lot better than Cornell. Whether it's worth the cost is for you to decide, but I am confident saying CLS places a lot better into the areas you're interested in compared to Cornell.
To qualify that, however, I'd say Columbia is noticeably worse than Harvard or Yale (I'm a little surprised you haven't been accepted to the former with your numbers), and at any school prestigious PI and appellate lit is a crapshoot, and requires you to be near the top of your class (even at H and Y). I'm sure you know this, but just wanted to make sure it was in your mind.
I don't have any rigorous statistics, but to put some color around it, you might want to take a look at these links (for all, adjust for class size):
-Mayer Brown's appellate practice (one of the best in the country) - there are 3-4 Columbia associates (which is still a lot less than H and Y), but none from Cornell. (http://www.appellate.net/attorneys/default.asp
-Kellogg Huber - top appellate boutique (--LinkRemoved--) has a couple of Columbia associates
-Skadden Fellows (probably the most prestigious PI fellowship you can win) by law school for the last two decades. Columbia places 1-3 typically, versus 0 most years and 1 every now and then for Cornell.
-Williams and Connolly on campus recruiting (they argue a lot of supreme court cases for a big firm) - http://www.wc.com/careers-summer-schedule.html
-Columbia postgrad PI employment (not comprehensive - also has other good resources) http://www.law.columbia.edu/center_prog ... yment/2009
-Contrast with Cornell PI employment stats (--LinkRemoved--)
It's hard to draw too much from this because the sample size is so small for each data point. That said, you simply don't see Cornell grads in appellate lit and PI for the most part. Whether this is due to self-selection or something else, we can argue about until our faces turn blue.
Edit: Columbia also has a couple of "exclusive" fellowships with PI organizations. For example:
-Kirkland and Ellis Fellowship -open only to NYU and CLS students (http://www.kirkland.com/sitecontent.cfm ... itstatus=0
-Johnnie Cochran Fellowship with Neufeld, Scheck and Brustin - open only to CLS students (--LinkRemoved--)
-Variety of other fellowships - some exclusive, some not (http://www.law.columbia.edu/center_prog ... ellowships