How about a rotation that focuses on weights with minimal cardio for 3 weeks, then goes to a recovery week, then goes to a more cardio intensive 3 weeks? That way, you're mixing things up, and you can see what works best for you. And you can finish off the rotation by alternating the strength-intensive week and the cardio-intensive week. (Freely inspired by P90X, which has a similar rotation, but without the "cardio intensive" part of it.)