"Oh, the Places You'll Go" holds a special place in my heart. I had just made the difficult decision to leave my job of 10 years, which paid well and had outstanding benefits, but the cost was too high mentally and emotionally. I'd been mentoring a young woman at the time and we spent a lot of time talking about how major life changes can be hard to make but ultimately you're the better person for having gone outside your comfort zone.
I had no idea what I was going to do after leaving this job and was beginning to second-guess myself when, on our last day together, she gave me that book--the timing couldn't have been more perfect and its message was just what I needed to hear in the only way she knew I'd hear it. (She knew of my love for Dr. Seuss.)
And a close second is "Horton Hears a Who"! :)