Or 55" The normal domestic 757's are generally 37-39, yes.

However the 767's have 40", compared to UA's 38". American doesn't count in this comparison because their 76's don't have domestic F.

Since you fly out of ORD, you will find a LOT of 88's, DC-9's and RJ's and the 1 daily 757 to ATL. (Which I'm sure you know)

The 88's have about 2 less inches of pitch than American's though. I find the legroom (not pitch, actual perception of room) to be pretty good in the old NW airplanes in F (and I'm 6'3") simply because of the fact that the seats are a lot narrower. I personally HATE the seatback tray tables in F, but I just avoid that by trying to sit in the bulkhead. (The only airplanes from NW where this isn't the case are some of the A320s.)

Personally, I didn't mind the cloth comfort wise; it was just hard to clean and looked like sh*t because it was starting to age a bit.