I would/do use mapscape by Evolved (free):
http://evolved-software.com/
Lightmapped levels look very realistic. Here is my game "The Last Stand" lightmapped in mapscape:
It outputs to "dbo" format objects and all you have to do is apply a lightmap shader to the results plus there's a cool "flashlight" shader that simulates using a torch/flashlight to light up the dark corners of a lightmapped room.
The main advantage of lightmapping is it takes virtually zip to draw and can simulate multiple lights and some cool lighting techniques such as global illumination and ambient occlusion for quite realistic levels with nice soft shadows!
Give me a shout if you get stuck!
