I occupied a lower berth in regular service on the UP's "Butte Special" back in 1968. The car was one of the "American" series 6-6-4 Pullmans that had a small buffet replacing a section and a toilet; across the aisle the section there was removed for a table and chairs. Another section had the portable table installed.
A few years later I shared a section with a friend on a Pacific Railroad Society excursion train. It was a two night trip and so we swapped around which used the upper berth and which had the lower berth.
Brian