ahh yes. a reoccurring topic in these forums.
From my own experience, radiosity is not the way to go.
There are various rendering solutions you can use.
For example, for the Safety animation my team did, we used a Mental Ray shader called Ambient/Reflection Occlusion shader to generate Global Illumination(GI).
Here's a good link that explains more about the shader:
http://www.christopher-thomas.net/pa...ion_shader.htm
Or
you could always use skylight + an HDRI image.
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These two are what I'm used to. I would recommend Final Gather, but I can't stand waiting for the looong calculations...
Good Luck!