My favorite rotation is the one I'm doing now! I am on week 3 of a 4-week Gym Styles rotation I made up myself. Basically it's 3 days a week of the three Gym Style strength training dvds, and three days of cardio. I add abs on two or three days -- something from Butts & Guts, Ab Circuits, or Core Max. The cardio is whatever I'm in the mood for, usually one step routine, one kickbox, and one outdoor hike every week.
I've noticed significant improvements... the first time I did the push-up drop sets in GS Chest and Triceps I had to skip some push-ups, and do them all on my knees. I dreaded doing them ever again! But by week 3, I didn't have to skip any, and I did the first five push-ups on my toes (a huge deal for me!) Also, I had very significant DOMS for days after the first week of Gym Style Legs, but this week I only had moderate DOMS for a day.
My weight hasn't changed (I don't want or need it to) but I think I might have lost some inches; haven't measured yet, but my clothes feel a bit looser and my husband commented the other day that my butt looks smaller.
I'm starting STS soon, and I'm excited to see similar strength gains since the format is somewhat similar to this rotation. Before I start STS, I'm going to give myself a couple weeks to play around with Cathe's new releases that will be out soon!