In a nut shell, I am exporting a postscript file from the Print Booklet feature in Indesign.
Why not export a straight PDF from Indesign you may be wondering? Because it is not paginated.... I don't need to print in logical order, 1,2,3,4,5... Rather the spreads with page numbers 36/1, 2/35, 34/3, etc... And the only way it seems to be able to do this (without me having to do it manually) is to print booklet and choose PostScript.
All is fine and dandy until then, but when I proceed to open the saved PS file in Preview, it opens it vertically instead of horizontally chopping off 3.5 inches from the right side of the booklet. (my book is 11 x 8.5, folds to 5.5 x 8.5)....
Rather than leaving your export ppd as device independent — choose a ppd (probably doesn't matter much which one) and set your paper size to custom (it should load your paper size in the relevant width and height fields automatically).
So, rather than this :
You should have something like this :
That way you are specifying a particular paper size rather than letting Preview do the PDF conversion using whatever generic size it works with.