I had to laugh when I saw this thread because I was creating a new rotation for myself today, and I needed a lower body workout to balance out Ramped Up Upper Body. I think Lower Body Blast would be a good choice. I also like the premix in the Kick Punch and Crunch / Legs and Glutes DVD that combines both workouts, so you are getting kickbox intermixed with intense lower body strength training.
Funny I just did Ramped Up Upper body 2 days ago, still sore, and FS Boxing Bootcamp/Legs and Glutes yesterday. Personally I would be drained combining both of them together, but if you can do it, you are one powerful woman.