Best workflow for buildings you can walk into

Love this tool!

Ok, so using the great speed modelling tutorials online, I have come up with good workflows for creating exterior buildings and for creating interiors (flipping normals).  For my more complex buildings, I'm using a new scene to show the interior (Skyrim style for lack of better term).  However, I'm looking for the best method/workflow to create a building you can see outside and walk into (look through windows, etc).

What does everyone use here?

Boolean ops to cut out the center of the room (which makes the faces wonky, but seems to work ok)?

Extruding around the center of the room?

Cutting out doorways (but if so, how are you recreating the faces where the tris were cut)?

Any functional or creative ideas are most welcome.

Thanks!