Physical imitations, both of the space available to me and of my own motor skills mean that I strongly prefer e-books. That said books whose aesthetic appeal is strong enough stay, like the Discworld map collection and the beautiful bilingual tri-scriptal(my coinage) Dialogs of Pyaasa. Still on the look out for some drop-dead gorgeous Sadi too, if I can find them with caligraphic Persian Nastaliq on one side, English on the other.