Having read this thread, I have now switched from 7L to 9L and back again. And I may yet go back to 9L.

I have something of a hybrid question. I'm flying WAS-SYD in December. Through luck, I got a United saver J award on Air Canada from YVR-SYD, which led to a bizarre, four-segment routing (DCA-ORD-SMF-YVR-SYD) for 99K miles.

Then, Air Canada moved my flight by what I thought was three hours later but was in fact a day plus three hours later. I thought this was a sufficiently long schedule change to merit a call, so I called United, which offered me DCA-IAH-SYD or IAD-LAX-SYD. I took the former option. That means a 737-700 DCA-IAH and the 787-9 IAH-SYD, all in J.

I am now debating two things: Where to sit on the IAH-SYD flight, and whether I should ask if they'll route me IAD-LAX-SYD instead.

The advantage of IAD-LAX-SYD is that it's 777-200s (currently both in Polaris configuration) the whole way. I know IAD-LAX will be domestic First service, which I why I picked the shorter, DCA-IAH domestic leg. But now I wonder whether the additional width of the 777 Polaris seats versus 787-9 on such a long flight makes it appropriate to (try to) switch. For context, I am 6'3 and 240 lbs., so space matters.

If I stick with the 787-9, my options are 7L or 9L. No row 1 or 9A available. On non-Polaris seating, the small footwells were an issue for sleeping. But I don't recall quite the same concern in Polaris. Meanwhile, I'm concerned about being woken up by bathroom traffic, since I sleep sort of lightly on planes.

Any thoughts? I realize this is a first-of-first-world problem, but (a) okay, (b) I earned those miles the hard way, and (c) it's a nearly-19-hour flight that will cap off 24 hours of traveling.