Calculus book suggestion

Thomas and Stewart are both standard texts used in introductory calculus classes. They are of a kind—they are not terribly rigorous, break things down into tiny little digestible pieces, but neatly avoid most of the interesting theory. If your only goal is to learn enough calculus to perform computations, either book would be fine. That being said, I would recommend against them—I wouldn't consider their use "unethical," but I don't think that they are good introductions to what mathematics really is.

I might suggest one of the following:

• Lang, Serge, A first course in calculus. 5th ed, Undergraduate Texts in Mathematics. New York etc.: Springer-Verlag. XV, 624, A99, I3 p. DM 128.00 (1986). ZBL0608.26001.

  Lang is pretty approachable, and has some nice examples. Lang's text also seems to find a nice middle-ground between the rigour and application—he elides a lot of the theory (though not to the point of uselessness), and does a good job of giving intuition. It is also possible that you might be able to find an older, cheaper edition running around somewhere. Lastly, my recollection is that there is a really nice section on Stirling's formula near the end, which may be worth the price of admission.

• Courant, Richard, Differential and integral calculus. Vol. 1. New edition, Glasgow: Blackie & Son. xiv, 615 p. (1937). ZBL0018.30001,

  There are actually two volumes here. Contrary to many modern authors, Courant first introduces the integral, then differentiation. Personally, I think that this is a lovely and natural approach, though your milage may vary. The writing is a bit old-fashioned, but this may be good thing. ;)

• Apostol, Tom M., Calculus. Vol. I: One variable calculus, with an introduction to linear algebra. 2nd ed, A Blaisdell Book in the Pure and Applied Sciences. Waltham, Massachusetts-Toronto-London: Blaisdell Publishing Company. A division fo Ginn and Company. xx, 666 p. (1967). ZBL0148.28201.

  I am less familiar with this particular text (again, I think that there are two volumes), but it comes highly recommended from colleagues. In other texts, Apostol is quite approachable—his exposition is generally quite good, and he builds up abstract ideas in a clean manner.

• Klein, Morris., Calculus: An Intuitive and Physical Approach. 2nd ed. New York, John Wiley & Sons, Inc. (1977).

  I recently picked up a copy of this text, so am adding it to the list since I think that it is very nice. The exposition is clear (though perhaps a bit verbose), it is rigorous, and does a good job of going over the standard curriculum. It also includes some good historical context, and spells out notational conventions which often trip up beginners (for example, his discussion of $\Delta t$ as a single symbol is spot on).

If you hadn't already ruled it out, I might also have suggested Spivak, but, as you say, his text requires a bit of work to get through. The work pays off, but Spivak can be intimidating, and it is understandable that you might want to consider something a bit more approachable.

Stewart is the standard. I happen to like it a lot. Also, if you are working through it on your own the nice part about it is you can purchase the accompanying student solutions manual that has all the exercises worked out for you. The overly long edition is likely the one that includes multivariable calculus. There is a shorter edition that does not include it. With regards to the lengths of these books in general, unfortunately there are no shortcuts in learning, the only way to learn the material is to...learn the material :(

Calculus by Thomas Finney has a nice modernized approach to it with computer based problems and hyperlinks to various visualization and images .