I have a few very near and dear favorites that I re-read over and over again. Like a previous poster said, sometimes I just pick a page and start reading.
My favorites are:
The Trumpet of the Swan by E. B. White
A Little Princess by Frances Hodgson Burnett
Little Women by Louisa May Alcott
Jane Eyre by Charlotte Bronte
100 Love Sonnets by Pablo Neruda
Harry Potter by J. K. Rowling (the first books in particular when I need a pick me up.)