I second the nomination of Analysis by Steven Lay. It's a great introduction to proof techniques and analysis, and it isn't that long of a book, which makes it great for a preparation book. If you could give a little more detail on the topics of your course, that would help. Different courses can mean different things by advanced calculus.
The calculus books by Richard Courant or Tom Apostol are excellent and rigorous presentations of calculus and basic analysis, but probably aren't texts you can go through over the Christmas break. Probably the best rigorous calculus book is by Michael Spivak, but again is something you wouldn't want to rush through. I've also heard good things about Understanding Analysis by Stephen Abbott, which would be aimed closer to what your course will probably be like, like the Lay book.
This is a joke right? I'm sorry, but Stewart has to be the worst recommendation as preparation for an analysis course ever.