The other great thing about The Pit is that newbies can have fun following along. There's no penalty if the newbs just stay on the ground in the hardest Mario parts (the furnace rooms). First-timers won't know the map, but they can easily make it up and down the central shafts if someone is guiding them. Then some of the rooms have puzzles where newbs can participate, and not just in the hack'n'slash.
Coalescence Chamber is the opposite on all of the above points: EVERYONE has to do the annoying climbs. Knowing the map doesn't make the endurance climbs less annoying. The room fights are generic and boring.
I like The Crucible. It's very manageable on Normal, and it's a good challenge on Elite. Fun fact: The swim CAN be done reliably without taking a single hit. It's just that most people don't want to practice it on Normal before joining an Elite group-- and understandably so.
As a matter of practicality, it's a crapshoot whether you'll get an elite-capable swimmer in your party. That's rough now, because Bravery streaks have reduced the fraction of veteran players willing to run quests on Normal.