Jacket pockets - for those of us in countries where the temperature goes low enough. I spend most of the year wearing some form of clothing that has a pocket that comfortably carries a Kindle - I don't have to specifically shop for the size, it just fits.
That means I always have my Kindle on me when I find myself sitting on public transport, when I arrive somewhere early or through lunch. It becomes the alternative to social media on your phone - and broadens your mind.