Doing a lot of transcons, I always book 18 D/E. Both row 18 and 19 give you more leg room than you could ever need. That's length-wise, not width-wise. Prefer row 18 because there is only one other person in the row but always prefer F for the extra seat width. Other than that, these are nice seats for Y.

BTW, these a/c also are used for TATL's but row 18 is not EC. The 75E's only have EC on the left side.