Expensive binding that will last; covers that are a pleasure just to hold. Nobody like to read super small fonts on crappy quality paper, but there's a real pleasure in seeking out and buying a really good quality book.
I've even done this with books that I've read in cheap paperbook format and enjoyed so much that I want to own one (or in some cases, more than one; usually when my search reveals something unusual - for example, when I went looking for a copy of Marisha Pessl's "Special Topics in Calamity Physics" I found a hardback ARC print that came with some extra bit n' pieces - a little pack that must have been sent to a reviewer by the publisher). Sometimes the good printings sold out years before and I have to track down one second hand in perfect or near perfect condition.