The seats are miserably under sized. I'm an exemplary normal size at 5'9" and 165 lbs. I did observe that many, if not most passengers are obese and fill about 1.5 if not 2.0 seats of this construction. Passengers who are seated on the same row are compressed by hot fat and stink for 3 or 4 hours. Not desirable. The Pittsburg to Denver flight was full. A mercy that the 737-900 has big turbo fans to push it up and fast.