Originally Posted by
WineCountryUA
The OP only has the short PHL-BWI flight on US metal and "preferred seating" in economy class on that route tends to be a joke. The rest of the itinerary is on UA which tends to grant *G benefits to UA*Gs in the OP's kind of situation for UA metal flights.
*G gets extra checked baggage allowance and at least also priority check-in and priority boarding too when dealing with the US flight.