Have an upcoming trip planned for LAS for Feb 8-Feb 11, I am debating whether to book with AC or UA.

How low can fares get for Feb? It's quoting me around $230 CAD before taxes now and I am sure I've seen as low as $100 CAD couple weeks ago. I am definitely not getting V or higher just so I could upgrade because I will get 100% Q miles for either L or V class anyways and it's not worth paying 100% more for V class to upgrade the 2 hour YVR-SFO flight on AC metal and stay in Y for the SFO-LAS UA metal. {More disadvantage for not giving 25% for C class}

I was thinking maybe I should book with UA so I could get 10% off for booking online and I could have a chance at getting an upgrade if I could manage to get some 500 milers... otherwise, I'll get E+.

Any thoughts?