I'll reiterate the recommendations for Catch-22 (possibly my favourite of all novels), and Dune (epic universe building with philosophical stuff). And for something no-one else has picked out, Goodnight Mr Tom is worthy of its children's classic status, and it's one of those novels tangled in serious themes that can be read with just as much pleasure by the grown-ups. I had to 'learn' it for a book knowledge quiz when I was at school, and having read it n times for that I could still simply enjoy it :)

For the second part: is Bridget Jones' Diary better than the sequel? I read the sequel first and didn't find it all that funny.