This gent went around with a meter reading how much juice neighbours lights where taking up, and figuring out the cost. To sum it up, looks like LED’s save allot of electric (1-2 cents hour to run vs 5-10 for regular). But….the overall cost of LED’s is a factor of 10 in my experience….
http://www.cockeyed.com/science/christmas_lights_energy/christmas_lights_power2.html