Ok, I think I figured this out. I changed my default Calibre directory back to using a local folder.
I changed the Saving books to disk save template to:
Code:
{series} {series_index:0>3s} {title} - {authors}
Then I just use the save to disk -> Save only MOBI format to disk in a single directory option to save the files to Dropbox\kindle.
Changing my default directory for Kindle PC to Dropbox\kindle picks up the new mobi files just fine.
I then use Dropsync on my Android phone to sync the books to my phone.
Whee. Now my question is, is this setup going to break once I add my Kindle Touch to it?