thanks to both of you.
the issue with the open space at the bottom right is well taken. that is a large empty space. unfortunately, there's little to be done at this point. i could perhaps crop the lower third off, as Asher suggested, but that would result in a very long, narrow strip of an image, too short in the vertical dimension to produce a decent print. i had to do some interpolation as it was to get it to print at 12x36 with half-decent resolution; any more upsizing, and i fear i'd start degrading the image visibly.
as for post processing, there wasn't a whole lot involved. i stitched the three frames together using Arcsoft's PMK3 software, then played a bit with levels and contrast to give it a bit more pop. i also brought up the blues a little, to enhance the blue of the water and sky. that's about it.
Rocky