I'm planning on lifting 4 days a week in an Upper / Lower heavy weightlifting template and attempt to throw in cardio such as spinbike intervals or sprints.
Most Fridays I try a cardio class like Zumba, Spin, or kickboxing, but if the class schedule does not fit my work schedule, then I will just hop on the treadmill, elliptical or a bike and spend 45 minutes on there.