There are a number of UA-metal-only $160 itineraries on ITA for 1/22-1/23 that would earn you great CPM with your certificate.
Example:
1/22
PHX-LAX-LAS-PHL-PVD
1/23
PVD-ORD-TUL-DEN-PHX
6253 EQM, which, after you apply your $100 certificate, would be $0.0095/mi.

(And even if you didn't, this would still be a very respectable 2.5cpm.)