The best undergraduate mechanics textbook I've seen is Morin's, though it probably requires a certain kind of student (one who is not fazed by taking things up one level). Morin does a great job of showing how experts actually solve problems (e.g., looking for symmetries, doing dimensional analysis, checking extreme cases) rather than just plugging in formulas. The downside is that if you just want to apply formulas, his methods can look like a bag of magic tricks.