There are a VAST number of ways to handle what you're trying to do.

The best way? Well, that's all up to you and what you're used to or familiar with.

For me to do something like what you're describing, I may attack it from a few different angles:

1. Build the first floor and prefix all my first floor layers with "FL1-", then build the 2nd floor and prefix all those layers with "FL2-". Doing things this way can show you where common items between the floors are...such as piping, wiring, etc.

2. Build the floors side by side (remember, you have an UNLIMITED amount of space in model space) and label them accordingly. From there, you can set up "Sheets" (Paperspace Tabs) to show each floor individually.

I hope that helps a little.

P.S. Do yourself a flavor and edit your email address out of your post. Otherwise you'll likely get hit by spam.

Good Luck!!