Possibly the best moment in Discworld is at the end of Guards! Guards! - showing Vimes and Sybil's blossoming relationship in the perfect terms — (paraphrased):
'What was it? Oh, yes... it's a one-in-a-million chance, he said, but it just might work.' And she smiled at him. It occurred to him that in her own special category of women, she was quite beautiful - and that was the category of all the women, in all his life, who had ever thought him worth smiling at. [...] The woman was a city.