Are the cabins the same between the -140 and -180 models? I didn’t think the -140 was a good fit for me and I wouldn’t want to sit for a long time in one.
They are the same in the front seat area; but -180s and all other PA-28 variants have more room in the back than the -140.
The Cherokee 150, 160 and 180 were originally all the same cabin, with a full-size bench rear seat and large baggage area behind, with an external baggage door. The Cherokee 140 was introduced in 1964 as a two-seat trainer version with a 1950-pound gross weight (200 less than the otherwise-similar Cherokee 150). A rear cabin bulkhead was put in the -140 just about where the back seat went in the 150/160/180, and the -140 had no outside baggage door.
In 1965 Piper introduced a "2+2 Cruiser" option for the Cherokee 140 with 2150 lb gross weight, with small, snap-in seats right up against that rear bulkhead. With the back seats snapped in, there was no (zip, nada) baggage room.
The 1969 "Cherokee 140B" featured a restyled, molded plastic rear bulkhead that offered just a tiny bit of baggage room and a hat shelf behind the snap-in rear seats (still no outside baggage door), and that's the way the -140 was until the end of production in 1977.* The back of a Cherokee 140 was never as roomy or comfortable as any other Cherokee model. It was intended that way, as it was marketed as a loss-leader trainer, and Piper didn't want it to compete head-on with the more expensive models.
[*You'll occasionally find a '71-'73 Cherokee 140 with the old-style, flat rear cabin bulkhead. These were mostly the stripped-down, fleet-spec "Flite Liner" model marketed to Piper Flite Centers. A registration number ending in "FL" is a reliable clue that the airplane was originally a Flite Liner.]
The Cherokee 180, meanwhile, switched from rear bench seats to full-size individual rear seats in 1971. The fuselage was stretched about five inches for the 1973 model year, nearly all of it going to rear-seat leg room. The Warrior (1974) and Archer II (1976) also inherited this same stretched cabin.
I am not certain when or if this ever happened to the 140, but that probably doesn't matter.
The 140 never got the cabin stretch, or wing or tail extensions (or baggage door). The last Cherokee 140 was built at the end of the 1977 model year, and its exterior dimensions were still exactly the same as those of the first 1961 Cherokee 160.