I've been conspicuously absent from posting my 'this is my' - so I'll get right on it this week. And may even catch up on a few of the old ones!
My favourite book would have to be My Family and Other Animals by Gerard Durrell. An English family relocates to Corfu just before WWII. It describes the life of the Durrell Family on the island in a humorous manner, the cultural differences, and also richly discusses the fauna of the island. My copy was an old penguin, orange cover, with a huge dragonfly on the front. I've read and re-read it so many times...
Other contenders would be Oryx and Crake by Margaret Atwood, The Timetravellers Wife by Audrey Niffenegger, and After You'd Gone by Maggie O'Farrell.