I would agree with all of the suggestions thus far. I would also add anything my Eli Maor (e, the story of a number, trigonometric delights, to infinity and beyond, etc.), and "Excursions in Calculus: An interplay of the continuous and the discrete" by Robert Young, published by the MAA (I think Dave Renfro may have referred this to me at some point ... perhaps I do not remember that correctly, though). Dunham's stuff is great, as is much of Ross Honsberger's stuff (MAA). I would also recommend Bressoud's "A Radical Approach to Real Analysis." It's an analysis book, obviously, but I think it follows the "Genetic approach" quite well, particularly in how it develops infinite series.
I've found that students are much more engaged in your mathematics class when you can show them that mathematics is perhaps one of the most impressive creative human endeavors, and not just a bunch of axioms handed down to us on stone tablets by some sort of math deity. They get so interested in the human element of mathematics that they have even asked if we can spend the last couple of weeks of class studying math history!! I think that's GREAT!