My studio uses DVIDA's syllabus, so we refer to Ron Montez for rhythm and the Marantos for smooth. I've also gotten Corky & Shirley's cha cha and samba routines which I liked, and their technique taped which I also liked. I've used Victor's old Standard tapes (before they were re-recorded with Heather), all of which were valuable.
I like these tapes because they give the foot placements, timing, and footwork, then give some good technique and partnering tips. You still have to know how to lead to use them, but they're about as comprehensive as I think you can expect in a video!