Originally Posted by
VWang1111
…If you use miles on a flight that offers complimentary upgrades, you have higher priority than all other complimentary upgrades including top status like 1k.
In reality, a lot of people will still be waitlisted ahead of a Silver requesting a mileage upgrade on longer routes. Silvers should not be expecting high chances of CPU or mileage upgrades on any transcon route. Usually the best benefit is a E+ seat, and even that might be a middle seat on packed flights.