Holy crap. I was just poking around in the options that are available in the stock Precision Zen theme on my 9700. I found that this one theme contains both zen and today homescreen layouts. No more switching between themes for me.
I admit this may be horribly old news, but I just stumbled upon it and I'm pleasantly surprised.
Now they just need to make the theme builder so that you can have both types of homescreens inside a single theme! Right now if you make a custom theme, it won't allow you to choose zen or today as different styles...