Try some john grisham. If you haven't already. He immediately sucks you directly in from the first line every time and doesn't let go. Also if you're looking for a [i]real[/i] literary challenge in the way of such novelists as dan brown but far more technical, try a book called Cryptonomicon by Neal Town Stephenson. It's a book that will make you laugh, draw you in, annoy you, and challenge your intellectual capacity, but you will respect it and enjoy it thoroughly, most definitely.