The first that comes to my mind is the prologue of The Name of the Wind by Patrick Rothfuss. It's beautiful prose with this hint of sadness and at the same time epicness and mystery. It made me want so find out more about the main character and read more of this poetic language.

I also love the opening lines of Wyrd Sisters by Terry Pratchett: "The wind howled. Lightning stabbed the earth erratically, like an inefficient assassin." Describing the weather is a really common opening, but Pratchett manages to put his own humorous twist to it. It unites setting the "stormy, witchy night" mood with setting the stage for his humour. The comparison is so absurd and so pratchetty, it never fails to make me grin.