I find the sleeper chairs more comfortable than the sofa for sleeping at OKW, and I'm a heavyset guy. Most (but not all) sofa sleepers at OKW are the old style with the bars, even though they were reupholstered during the recent rehab. The chairs are a thick foam on a solid suface and sleep more like a bed than the sofas.
I was going to say that the sleeper sofas at OKW probably wouldn't be comfortable for an adult for an entire trip because my then 7 year old complained about it being uncomfortable.....but I see the sofas at OKW are the old fashioned kind judging by others posting