When the power is out and I have to run on the generator, it becomes obvious what uses a lot of power. (Well, there are watt meters on the transfer switch for one thing, but the generator audibly lugs down when a big load comes on too.)
The incandescent lights are HUGE. Even turning them down 30% with a dimmer switch reduces half the load without making them much less bright. Switching to fluorescents or LEDs makes a big difference. The other big load is the refrigerator. Everything else is pretty incidental. I suppose if one had electric heating it would be the biggest load.
On the boat, I'm hyper-paranoid about electrical loads, because the batteries have a limited supply of amp-hours. Some day I'll get some solar panels. Even though I've switched to all LEDs, still the lights are the biggest continuous load. Motors (pumps, engine-start, or windlass) are bigger loads, but they only run momentarily.