Yup, there's really nothing you can do to get it perfect other than use a circular polarizer or Merge to HDR.
I do what you do (focus near top of tree) when I don't have the time or inclination to post process that much. It's not perfect, but it's better than the other two alternatives.
To get to HDR in CS2 just go to File -> Automate -> Merge to HDR, and you select the files you want to merge. They must be shot on tripod though, or else the end result is really misaligned.
http://www.luminous-landscape.com/tutorials/hdr.shtml