Off the top of my head, the essential elements of a great pit:
- Organized and quickly accessible storage for any parts or tools needed for robot repair.
- A reasonable amount of countertop or table space to do work on.
- Enough room for people to work on 3 sides of the robot at a time. Robot can fit in "center" of pit with people all around it, with minimal spill-over into the walkway.
- An unobtrusive solution for battery / charger storage and use.
- Easy to load / unload; as many rolling or quick-assemble elements as possible.
There's a bunch of other features that make pits better (lighting, storage for everyone's jackets / personal crap, etc) but these are the vital requirements.
I'll try and find a picture of 2791's pit from this year later. We've been working on it bit by bit since 2011, and I really like where it's at now. A bunch of custom rolling cabinets, a few collapsible shelves, and our rolling toolbox make up two sides of the perimeter, and there's enough room in a 10x10 to put the robot in the middle.