For most of the time I've used Poser I kept my default scene very similar to Poser 4's.  I'd move the floating palettes around to allow for a larger preview, but for the most part I just didn't give it much thought.  I spent many hours with Poser in 2011/2012 and began giving more attention to my preferred lauch behavior.  With PoserPro 2012, I found the hardware preview warranted a little rethinking of something I had always deliberately kept simple before.

A project I was contracted to do required a casual figure in an office environment.  Before modeling the props I decided it was probably a good idea to use standard dimensions for desk height, chair footprint, etc.  I know there were/are disagreements over Poser's units, but I also felt it only mattered that I pick one and stick with it.  I opted to use Fire Angel's Measuring Tools as the 10 foot rule exported easily into Wings where I'd be modeling the environment props.  Noticing that I had begun a number of characters over the years using different base figures I found it handy to add the 10 foot measure to my base scene to make it easier to gauge relative figure proportions.

With EZSkin I found I frequently needed a quick way to save the older materials that EZskin would overwrite, usually to copy the original's diffuse colour to the new material's alternate diffuse channel (not saying you should do that, just that I do it).  My solution was to add three more materials to the ball prop, and check it to invisible.  This gives me a handy dummy object to temporarily store/compare four materials while running mat scripts etc.

My ground plane is a farily basic ground texture with a gradient transparency over a grey background colour.  This gives a pseudo fogging effect that looks good when creating/modifying figures.  I use a single infinite light and (probably) ran the image gamma and/or Render Firefly scripts along the way.

I just thought I'd share this set-up as I don't hear much discussion of default scenes beyond how to delete Andy or some other such initial customization.  I'm interested in what other users have changed to make Poser more useful for their way of working.