Here's a PHL-LAX fare on UA. L fare basis code. I don't know if UA 2Ps get any bonus miles, etc.
From united.com, entered PHL-LAX 4 DEC Afternoon, return 4 Dec eve seach by price:

United Airlines 99
Airbus A319 Dec 04 6:00 pm depart PHL
Dec 04 8:49 pm arrive LAX stops: Non-stop
Class: Coach
Fare Basis Code:
LOA14AN
Booking Class: L
Fare Rules Everyday low fares

United Airlines 98
Airbus A319 Dec 04 10:10 pm depart LAX
Dec 05 6:07 am arrive PHL stops: Non-stop
Class: Coach
Fare Basis Code:
LOA14AN
Booking Class: L
Fare Rules Everyday low fares
Total Airfare (including taxes and charges): USD 178.20
This comes out to ~$.04/mile which would be too high for me, but if you get bonuses...