I got switched a couple of week ago on a 777 from ORD to SFO. I selected the flight because of the 2 seat (window, aisle) configuration. I was eventually even able to get an exit row window.

The day before departure the aircraft was swapped. UA eventually put me in 18A with no other available seats when I looked.

I hoped for an upgrade, but I was #36 on a list of 78.

At first I really felt crammed in. I was also annoyed that Group 2 was the last to board. Yes, they boarded Group I through Gate A and 2, 3, 5 through door B. Finally, they let Group 2 board through door A. We had to walk through the first class cabin and merge at door 2 with Group 2 - 5 that was already in the aisle.

After stewing for a while, finally had to convince my self that this is UA, and I had better get used to the new configurations. At least we had pillows in Y and blankets (thick sheets, really).

Once I got in the frame of mind that this is a "first world" problem, the flight was OK. I got there on time, I survived, and I am here to tell about it!