I've seen Willow Weep For Me done in the key of G with the second chord of the first measure being D+ and also C7. This is so in many different versions.
The D+ is used in Vol 2 of the original bootleg version of Standards from the late 40's.
The C7 is used in Real Book 2. Of course both of these books are notorious for wrong chords.
Both chords give a different flavor. I favor D+ unless I want to do it more bluesy.
I have also considered that the notes of both chords could be put together to create a C9(b5) or a C(#11).
Here's a version using the augmented chord:
http://www.youtube.com/watch?v=dFsY3HMTpoQHere's a version using the IV7 chord:
http://www.youtube.com/watch?v=gHmbzvGIPtkBetter versions out there, but these clearly show the two versions.
Either way a great tune.
What do you use and why? If you don't play the song, which one sounds better and why?