Leather is only available (from Toyota) on the Limited models. In some areas, you can get 'port installed' leather on the other trim levels. You can also have leather installed aftermarket. Search the forums for more info on this option.
Power seats are only available on the Limited model. Both seats are power though the driver seat has more adjustments than the passenger seat.
Navigation is only available on the Limited models. It is also possible to purchase a Toyota NAV system and install it afterwords. Several people here have done it. Search the forums.
The 115VAC options is available on all trim levels but may be difficult to get without placing a custom order (depending on what part of the country you're in).