Creating the interior of a house

I'd like to create some sort of game, like this one:

As you can see, this is a 1st person game. The character moves through different rooms in a house.

My question might seem a bit odd, but how should I design each room? Separately from one another? (For example, different 3D files/models for the Kitchen, for the Bedroom and for the Livingroom). OR, should I make the entire house in the same 3D model?

The drawback of this last alternative is that it would VERY tiring to manipulate the whole 3D model. Any hints?

Thanks.

 

Hey, any help? Thanks!

 

Pro 1 file per room:
If you update a model it does not take so long (especial if you need to generate light map uvs)
Con 1 filer per room:
It could get a bit messy if you have like 15+ rooms.

Make it dependent on the amount of geometry and how easy you can break it down to useful parts.