YVR Cockroach

In addition to the 777 and 787 both of which have had seats added widthwise (the 787 before it even entered service), there have been at least 3 widely-implemented seat width reductions. The early 747s, DC-10s and L-1011s usually came with 9 abreast for the former and 8 abreast for the latter two. Don't remember when they being changed to 10 and 9 abreast respectively.

Britannia Airways' (BY') 767-300s had an incredibly-tight 8 abreast if you can imagine, 320-something pax birds. Not for short flights but at least as far as LHR-YVR (8-9+ hours inflight time). I even remember some travel marketer in a British sunday paper travel supplement advertising that with a seat diagram (real good selling point, I am sure).

As for cabins, fuselage cross-sections are not circular. Boeing's narrow bodies are ovoid (vs Airbus having round fuselages) so the curvature inwards isn't as bad as Airbus narrow bodies.

Also, Boeing usually to places the floor below the widest section which gives a little more hip and elbow room while Airbus places the floor at the widest section (hence why Airbus pax aircraft gave great cargo payload) which results in rapidly narrowing shoulder room.

I've seen comparison graphics before but can't find any off-hand.

airsurfer

That must be before 1975.
From that year on, until the 1990s I flew often 747 and DC10 which were all 3-4-3 (10 abreast) resp. 2-5-2 (9 abreast).
And, I must say, that despite my height of almost 2 meters, I have less problems with legroom in modern aircraft (777, A380, barely 747-400) than in the 1980/90s. I am talking about EU <=> S America / Africa / SE Asia / Australia / Oceania routes.

Maybe the situation of US airlines is/was different.

weero

You sure it's ovoid? I think the section above the floor plate is pretty circular and so is the section below but they have different radii.