multi floor drawing set up

I've got a rather broad question but I'm hoping someone can help provide some guidance as to how I should set up my drawings.

Our office is using AutoCAD 2009 and just got TSIs CAD-DUCT. We're new to the BIM/CAD-duct world and no one in the office has the experience to guide us.

Here's the current situation:

We're the mechanical design build contractor working on a three story building. The architect has provided us with the entire building drawn in 3D in one AutoCAD file. I'm struggling figuring out how to best work with the file. Normally we've worked with each architectural floor in a separate file which we would then xref into our floor models. But this time the architect won't budge and break up the file into multiple floors. I don't want to create three different architectural files deleting the two floors that aren't required for each drawing if I don't have to. It just seems like it would be a lot of time wasted each time I get updated architecturals. I tried playing around with the 3dclip command but that doesn't seem very precise (I'm eyeballing the cut lines) and it doesn't carry over to subsequent plotting drawings.

Does anyone have any tips and tricks for working with multi floor architectural drawings?

Maybe I should just put all the duct work for all three floors into one mechanical drawing. I suppose that would have some benefit, all the risers would actually be connected. But it would have it's negatives as well. Duct elevations on the second floor would have global bottom of ducts rather than BOD from each floor. Not to mention the file size would probably quickly get out of hand.

Please share any advise, and thanks,

I would try to set it up with the DVIEW command. Once active, the command has several options available:

[CAmera/TArget/Distance/POints/PAn/Zoom/TWist/CLip/Hide/Off/Undo]:

Select the CLIP option to set up your clipping plane. You can set the clipping plane at a specific elevation. You can also turn the clip on or off with this option.