I don't find significant differences in the F seats on the 737 and MD80; I'm fine with both. However, I was planning for an award trip earlier last week, and I came across ORD-SFO being flown by an MD80. It is definitely not comfortable in the rear of the Y cabin on an MD80 for a ~4 hour flight. While SFO is certainly not the same as LAX in AA's vision, flying the route with an MD80 is just .