Wow! The United Airlines Fleet Site is a magnificent resource. Having now studied it, I am able to focus on the aircraft types that are in service then come back to the others at a later date once they return to service. One observation: the nifty 3D cabin views on United's site are great but I have now come to the conclusion they are not all entirely accurate.
The Polaris 777s have now been
uploaded
Boeing 777-200ER
Boeing 777-300ER
I'll turn my attention to the seven-sixes, seven-fives and seven-threes next