This is actually something I've struggled with as well here at our firm which does a lot of coordination between disciplines. For most of our projects we decide to go with the slab in the structural model, mainly becuase most slabs are structural and the Structural Engineer needs to be able to run analysis or edit the structure of the slab assembly at any point of the project. The issues here are many and include:
1) When the slab is part of the structural model, the Archtiect can not place floor hosted elements in the model, he must use face based models (which lack in the out-of-the-box family library).
2)The architect can not see the changes that the structural engineer has made until he receives the latest and greatest model meaning he doesn't know that he's going to have to move those 50 walls he just modeled to create that funky looking exterior wall facade becuase the slab had to grow by an inch to accomodate the correct structure.
Probably one of the most effective ways to accomplish what you want is to have the architect copy/monitor the slabs into their model. My understanding is that this will psuedo copy the slabs into their model, allowing them to make adjustments but not make the adjustment permanent. Although i have never used this feature, I think it basically tells the Engineer "Hey, the architect wants to do this to the slab. IS that ok?" and the decision on the change is up to you.
Now, the monitoring of these elements is only as recent as the file that they are copy/monitoring from. So if you change something, the architect obviously won't see this change until you send him the updated file. When the archtiect gets the file, all elements that you have modified will alert the architect to the changes so long as he has the copy/monitored. So there is a complex level of coordination that is needed (for instance when you're working on slabs, let them know so they can copy/monitor all the slabs, or when you're working on columns, let them know so you can copy/monitor all the columns) for these notification to work.
To get a good idea of the function of the tool, search for Monitor in the Revit help file.
HTH, and best of luck!
Carl - rkitecsure[at]gmail.com
Need help? I'm probably in my chat room!
You fell victim to one of the classic blunders. The most famous is never get involved in a land war in asia, but only slightly less well known is this! Never go in against a Sicilian when death is on the line!