I've found a way to make a region that looks like it FLOATS. This WON'T require any mods or plugins, and is actually VERY simple.
1. Go into Documents/Simcity 4/regions and make a new folder (name it what you want to name your region)
2. Open the folder and make a new bitmap image (name it 'config'!)
3. Open the bitmap image with a painting program (I use Paint.net)
4. Re-size the image so that it is 24x24 pixels (I have never tried larger, but you can certainly use smaller sizes!)
5.Add in pixels that make up the region spaces. Here's a legend to what makes what:
4x4 blue pixels for a large city
2x2 green pixels for a medium city
1x1 red pixels for a small city
white pixels for nothing but air
Here's an example of what it should look like
Now, go into Simcity 4, go into 'Load Region' and click on the region you created and have fun!