On many widebodies the fuselage is narrower in the last few rows; but they tend to have 1-2 fewer seats across to compensate, so this can sometimes mean slightly more shoulder room. On the other hand, you couldn't pay me to sit in the middle section sandwiched between two lavs at the very back.

Also, 777's in particular seem prone to "lateral oscillation" in the way back in even minor turbulence. I remember one flight where I could see the ripple in the sidewalls as my row fishtailed back and forth. It wasn't enough to make me airsick, but I did feel a bit queasy.