I boarded through door L2, which is between the two Polaris cabins. United’s Polaris cabin on the 777-300ER is massive, with a total of 60 seats. There are 28 seats ahead of the second set of doors, and 32 seats behind the second set of doors. I was in seat 18L, which is the window seat in the last row, so I walked to the far aisle and then turned right.
While each Polaris seat features direct aisle access, the seats alternate between being closer to the aisle and being closer to the window. Odd numbered seats are more private and are further from the aisle, while even numbered seats are closer to the aisle.
For example, below is a picture of seat 17L, which is a “true” window seat. The advantage of this seat is that it feels extremely private, as you basically have your own cocoon.