My current faves, today at least, and in no particular order are
London - Edward Rutherfurd - brilliant book, made me really enjoy my visits to London.
Treasure Island - R.L. Stevenson - One of the first "grown up" books I read.
Diary of Anne Frank - I felt like an evesdropper when I read this. Always reduces me to tears at the total injustice of it all. Visiting her house is on my "things to do before I die" list!
Any of Agatha Christies' books - I know, I know that means it's more than 5, but I find it impossible to choose a favourite
Narnia Chronicles - C.S. Lewis - again, more than one book, but had I not read these then I probably wouldn't have gone on to read Tolkien.
The Hobbit/Lord of the Rings Trillogy - Tolkien - I was given these by an ex boyfriend to take my mind of the long train journeys to and from seeing him. I managed to lose myself in these books and the time passed in an instant. I think the movies are very true to form, although I would have loved to have seen Tom Bombadill created in celuloid.
The Chamber - John Grisham - Hard to pick just one of his books, so I picked this one. I am a big fan of his work and have all his books.