Loading a map/scene

What would be the best way to load an interactive complex map or scene?

Using a model for the whole scene, making your own file and creating models and etc according to stuff in the file, using a model as the base for the scene and using your own file to add other models to the scene?

Thats kind of how I do it.

I also "tag" geometries in the "scene base model" by giving them special names. If I f.ex. call a box in the model DOOR_1_0_0_01, my loader will create a door nr 01 that slides open in the (1,0,0) direction.

Thats a temporary solution though, until I get the time to make my own exporter for Blender.