I understand what you are trying to show; we do a similar thing here (manually, as far as I know).
Without an anchor, a tag is just a Multi-View Block that is not pulling data from anywhere other than what you manually enter (or have set as default values). A single tag can only be anchored to one space. If a single room only ever had doors opening out onto a single other room, then you "might" be able to use a location property on a Space, to read in the floor finish on an adjacent Space, then display both the Space floor finish and the "read-in" floor finish of the adjacent Space in a single tag. There could be issues with getting the order right for all possible orientations, however, and, for me at least, the deal breaker would be that there will almost always be Spaces that have doors into multiple other Spaces and at least one where you would need a two different flooring transitions.
I agree with TeamSquid's suggestion to set up a tag that shows half of your graphics (and displays the floor material for the Space to which it is anchored). Pop two in at each flooring transition and you should be good to go. You may need to be clever about the way you format the graphics so that it reads properly in all orientations. If the graphic convention is fixed, you may need several different tags, to suit various orientations.
David Koch
AutoCAD Architecture and Revit User
Blog | LinkedIn