Generally I take a week off training completly every 10-12 weeks, no cardio. I increase my calories a little by eating more than my fair share of ben and jerry's. I try and sleep that bit extra too, also a deep tissue massage during your week off can really work wonders to aid recovery. Also the psychological element to a week off can create a burning desire to get back to the gym.
When I do return I spend the first few weeks evaluating certain excersises, seeing what works best for me and what doesn't, what changes I need to make and bodyparts that need to be improved, from week 3 till 8 I tend to go all out with high intensity, forced reps, extended sets, rest pause etc., then from week 9 till 12 I bring down the intensity, just training a rep or two short of failure, then a full week off.