Here's how I go about such a scene...

1. make all bodyparts invisible that are covered by clothing
2. remove all unnecessary texture maps (for parts of your scene that are not visible, like an inner mouth texture, when the figures mouth isn't open)
3. turn off "visible to raytracing" for transmapped hair (if you can get away with it)
4. check render settings
5. render at small size, but same ratio of final render (like 400x400 instead of 2000x2000)
6. start final render right after you got a small render that was ok.
   (in that case, Poser loads all textures much faster, as they are still cached!)

That's how I did this render (http://www.renderosity.com/mod/gallery/index.php?image_id=1910863)
Took about an hour to render, twice the size that was posted to the gallery.
Scene uses IBL/AO some spot lights, all figures with high-res textures, some of the clothes
shading rate set to almost zero
OK, cloth doesn't matter that much in this image :-)

Currently I have a render running, with 4 x V4, 3 x M4, all fully clothed + some props with lot's
of transparencies and raytrace reflections...
It's been rendering for about 30 minutes and shouldn't take more than another 30-40 minutes...
Image size about 2500 x 1500.

So, Poser 7 can handle such scenes :-)

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