"Seek out and sleep in 20 opulent beds across Alyria." There are apparently more than 20 beds around Alyria, UG and FP. You only need to sleep in 20 of them to get the mark. For example, archons will not be able to access the beds in lower level areas and lowbies also are not expected to explore the high level areas for the beds. Any 20 that you can access at your level will work.
Fluke noted that number twelve (12) did not seem to work. They were checking the entire area with Pense up as well. - Cordarei
You go to sleep in an opulent bed. You snuggle down into an opulent bed, looking happy. You have slept in 20/20 beds. For displaying your love of sloth and comfort, the Powers have granted thee the Mark of Opulence. You have been granted the Mark of Opulence! You gain 100 archon points! You gain 94 practices! You gain 1,000 building points! Something appears in your inventory... You seperate yourself from an opulent bed. You focus your powers of observation on a compact traveler's bed: Item 'a compact traveler's bed' is type furniture, alignment 0, made of cloth (in (new) condition), has keywords 'traveler compact bed'. This item weighs 0 stones and 10 pebbles, and is valued at 5,000 gold. This level 10 item has the attributes: identified owner-only insulated wont-fuse will-float save-location unique This item may be used up to 500 more times. *This item has a limit of [1] per character. *This item belongs to Minotorious. This cot is fashioned out of soft white cloth that's been strapped to a frame made of a petrified whitewood that seems surprisingly strong. It seems to be fairly easy to fold up and carry with you, and might be handy for a more restful sleep whilst journeying through the wilderness regions of Alyria. While strong, it's also surprisingly comfortable despite the lack of extras. The taut cloth is oddly relaxing, and who needs pillows anyway?