Kobo Mini: I just bought one of these for hiking. Without the snap-on decorative back it weighs 117 grams, (48 grams less than my Sony) so I will certainly choose it as a dedicated hiking book which I can leave in my pack all the time. The ‘Mini’ has a 4 gig micro SD card inside, but only uses @ 2 of this – though this too can be changed. It is possible to upgrade the storage (say to 32 gigs – worth a try) so that it will fit all your books.
il, Facebook, The Kobo Mini has wifi and a micro browser so you can surf the Net one tab at a time, check your email, shares etc. With the wifi turned off they claim about two months battery life, so PERFECT for the trail. This particular model is no longer for sale, so I suggest you snap one up off eBay (which is what I did) pretty soon, before they are completely unavailable:
http://blog.the-ebook-reader.com/2013/10/08/how-to-expand-internal-storage-of-kobo-ebook-readers-video/ & http://www.mobileread.mobi/forums/showthread.php?t=209122
PS: A new model is now available with touch screen.