It would be nice to be able to edit spaces (or have another category for adding a combined rooms space) to include several rooms and then choose which of the selected room's information to use for the room-combined space.
This would help the lighting calculations and HVAC load calculations in models where the architect goes crazy with room separation lines and once the architectural model is linked into the MEP file and you set the Revit Link to be "Room Bounding", you have a bunch of different "Rooms" inside of what should't be designated as separate rooms but rather areas within the same room. The MEP designer is then stuck with a file where spaces don't represent the true area we are intending to have calculations performed on or try to convince the architects to change the way they are using Revit. But this would involve having to keep every architect up to date which is rather combersome and sometimes not possible if in different offices.