Wow... good stuff. That is pretty much exactly what I was looking for.
I'll basically respond to my professor with this:
"The best recommendations offer substantive, enthusiastic assertions about your intellectual ability and strengths as a student demonstrated by specific, detailed examples. We want to hear about your writing ability, analytical skills, willingness to think critically and challenge your views, intellectual curiosity, motivation, and contribution to the classroom. In addition, relevant personal characteristics, such as work ethic, maturity, leadership potential, professionalism, and ability to work with others, often give us a more complete sense of what you have to offer.
The best recommendations bring these qualities to life through examples and comparisons – we love to read about specific examples of your work! Quantitative comparisons (e.g., applicant was by far the best student in my class and I would place her in the top five percent of students that I have taught) are extremely helpful. Illustrative anecdotes from statements that you made in class or during office hours, or a discussion of your analysis in a specific research paper can really give us a sense of who you are as a student. "