Many years ago I had an opportunity to sit in an original Eames lounge chair, the icon of luxurious seating. It was not comfortable for me: it was famously designed for a shorter person and simply did not fit my 6' body. Its owner in this case was a short man and it fit him like a glove. I have since found that many chairs are designed for shorter bodies and are not for me. Like you I can tell by the rolling of the shoulders that it is not right. I need to sit in a chair first before considering buying one - no internet ordering here.Today I tried out the high backed chair at West Marine. It has a good seat cushion and I like the way the seat back can ratchet into more than one angle. But what killed it for me was the way it forces my shoulders to hunch over. They make it a little bit thicker in that area, and I know it would drive me nuts after while. Lumbar area could have used a bit more material, perhaps, but that was minor.
Then I tried the low backed version. The back was flat and seemed fine, however the seat cushion is far less cushiony and my butt bottomed out immediately on the frame rear the rear of the seat.
The guy said the high backed chairs have become hugely popular with the rodeo crowd. They are loved by wives who have to sit in the bleachers all day watching their husbands ride. I can imagine that a 5'4" or 5'5" gal's shoulders would rest against the back at a lower point, which makes the chair ideal for someone of that stature. I'm only 5'8" but it just wasn't right for me.
Greg