I'm a circuit girl, too!
Cindy Whitmarsh's Ten Days to a Better Body has two, 35-minute cardio/weight circuits, and is one of my alltime favorite workouts, ever. Also love Amy Dixon's Women's Health Ultimate Fat Burn, which is 40 minutes (and the circuits are longer). Jillian's 30 Day Shred has a format I love (3 minutes strength, 2 cardio, 1 abs), but you have to be a Jillian fan, and IIRC the workouts are closer to 20-minutes. But the nice thing is you get 3 of them on one inexpensive DVD!
These are older suggestions, but I think circuits haven't been as popular lately.