Originally Posted by ethernal

United's 737-900s were a dream but unfortunately they are slowly refreshing them to a much denser config. The original configurations were 147 seaters and had a very, very large economy plus section (51 seats). Unfortunately their updated version is 179 seats, but they still have significantly larger Economy Plus section (27 vs. 21 on Delta, and 4 of the 14 aisle/window seats in C+ are bad in the Delta config meaning there are only 10 "desirable" C+ seats).

Long story short, the Delta 739 is bad for two reasons. One is that the airflow is terrible. The gaspers don't gasp - they whisper. Every flight I take on a 739 is an uncomfortably hot one. Number two, there are few good seats. The only good economy seats on the plane are 10A, 10C, 19A, 19C, 19D, 19F, 21A, and 21F. 21C and 21D are okay, but not great. The 757 has more "good seats", as does United's configs.

This is all aggravated by the narrower seats on a 737 (vs. an A320), but it doesn't seem to be the driver of disdain since 757s have the same undersized seats as the 739 and most people here like the 757s.