Actually, most new inverters tend to be quite efficient (90+ percent). There are some very small inverters that you can put in the cabinet with your TV so you can watch TV while not on shore power. They draw very little power and work very well. Generally, they will also power a satellite TV receiver as well if you like the good things in life!
If you want to power more than that then you are going to need more batteries and a bigger inverter with a good battery charger to get the batteries powered back up after a night of partying!