I wrote outlines for each of my recs.
That is, helping them know what to write. Reminding them of key accomplishments, awards won, tasks I achieved, elements they should include.
I.e. They should mention their own title and if they have an MBA, mention it, especially if its from teh school you are applpying to.
They should comment on your performance overall, and compared to your peers. They should talk about specific achievements you've made, and how that has helped. It should be a gushing thing. They should comment on your cultural sensitivity, team orientation, analytical skills, leadership ability, maturity, how "fun" you are to work with, etc.
I wrote a 7 page guide for each, specifically reminding them of how I was a leader for project X, or how I mentored person Y, or how I was fun because of X, etc.