Calculus, Introductory Edition, Volume 1

Direct competitor to Stewart, Concepts and Contexts 2/e (ITP, published 1/1/2001).
"Questions" woven into presentation of the material engages students in the learning process. See for example: "Questions" 1-6 on pp. 4-5 and their responses on p. 65
"Tune-up exercises" constantly checks students' skills. See pp. 14-15.
Section 4.1 in Shenk provides a great preview to integration, allowing students to ramp up to this very difficult topic. This feature is uniques to Shenk.