Hello, Passengers flying with united airlines seat selection can choose their seats either when they book their flight or at check-in. The process was easy and affordable for me, thanks to the clear visuals of available seats on the website. On my flight, standard seats did not incur a charge, but preferred seating and extra legroom were available for an additional fee. I opted for a window seat close to the wing for a minor additional charge, and it was worth it. Choosing my seat meant I could also sit nearer to my companion on the journey. All in all, it contributed to a more comfortable and stress-free journey for me.