I definitely have been to one. That was at the Concord Casino in New Hampshire's capitol city. The chairs were luxurious and it was like sitting on a cloud. I could hang the strap of my purse over the folding armrests and relax comfortably while I played a tourney.
I used to look forward to my monthly two day stays in the Granite State to play here Monday night, and then in Manchester the next night. Or I'd play at Manchester on Saturday afternoon, and then Sunday in Concord. It was a comfy little room like the one they used to have at the Sahara in Vegas. Sadly they had to close a few years ago due to the owner's legal problems.
I can't say that I have. I've always been comfortable in the chairs where I've played. There is one place however where if I wasn't careful when I stood up and pushed the chair backwards the weight of my purse hanging on the back would tip it over. It was still very comfortable while I was seated.
Of course I've never played one of those tourneys with 1000+ players. From what it looks like for most of them in the pictures I've seen is that they are most likely stackable or folding chairs. Of course that is to be expected when you are expecting so many people because the chairs are easy to store. Those definitely haven't looked too comfortable.