I just finished reading Hail, Holy Queen - The Mother of God in the Word of God, by Scott Hahn. I can think of numerous passages that stood out to me, and that were very eye-opening. But for my purposes here, I'll just mention the truths that stand out most in my thoughts right now.
For non-Catholics and even Catholics who don't fully understand who Mary is to us as believers, something is missing, something good: a mother for the church and for each of us. For me, this book was a good introduction to that - now I want to know more. Part of that will be more reading, and part will be praying the rosary.