United Airlines offers numerous ways to upgrade a seat to the upper-class cabin. Travelers can upgrade their seat on United with options such as a MileagePlus Upgrade Award, complimentary upgrades, PlusPoint Upgrades, and instant upgrades. Moreover, by making a United Airlines Seat Upgrade to first class, one can enjoy better services and various amenities. To avail more details about how to request an upgrade and the related guidelines, visit the official website of United Airlines or check out the blog at the aforementioned link.