Offer a 120 VAC inverter option, to power common devices. The outlet would be in the center area so a laptop or DVD player can be run and charged. To save power, it might only be active when the vehicle is on AND an item is plugged in. A system with 100-200 watts would be adequate for many uses.
A bonus would be a 240 VAC option.
A few vehicles currently offer built-in inverters. External inverters that power from the 12 V accessory jack are available now for up to about 150 W and reduces the need for this feature.
The Cybertruck offers AC power. Details are unknown as of this writing.