Originally Posted by
rustykettel
For instant upgrades, only need the 75K level (H or higher). However you can still choose the MVPG level (M or higher) when doing an instant upgrade as a 75K. Depending on the price difference, it might be worth the cost for CoS bonus.
Correct for an instant upgrade without a GGU. An MVP is also eligible on Y & S class fares. The OP was asking about using GGUs for instant upgrades with U availability. K class fares are the lowest fares that a GGU can be applied to for an instant upgrade.
The cheapest fare that is available for an instant upgrade (it could be higher than K if the K class bucket is already sold out) will be shown by selecting the Gold Guest Upgrade option in the upgrade type drop down list on the primary search or selecting the Gold Guest Upgrade radio button on the left side of the search results. GGUs are not tied to Elite Status (for application) and can be used by anyone with GGU codes. There would need to be 2 U seats available and 2 GGUs required to upgrade both passengers.
James