I never really considered the length of story to have any bearing on it's ability to draw me into the story. You mentioned works by Asimov and Clarke, two of my favorite reads, but at the same time I'm equally as happy reading something like Cryptonomicon by Neal Stephenson.Books are getting fatter – and have been doing so for decades. When I first started reading science fiction in the late 1950s, the typical full-length novel was no more than 200 pages long (about 80,000 words). This remained generally true throughout the 1960s but then books began to expand, resulting in today's doorstops. Clearly, the genre has something to do with it; Tolkien set a standard in the length of fantasy novels (as in so many other respects) and it seems today that no fantasy can be regarded as serious unless the story fills up at least a trilogy. However, SF has followed the trend, albeit more slowly. The question is – does quantity equal quality? Are today's novels better for being so much longer?