Like this?
While it isn't exactly what you wanted, it's fairly close. I just used the VerticalRacetrackTenSeatTableBlueprint*.xml blueprint twice followed by the RacetrackTenSeatTableBlueprint*.xml blueprint, and set the number of columns on the page to 2.
The vertical blueprints actually aren't included yet (they will be included in 2.6), so I've attached them to this post. Download the attached "blueprints.zip" file and save it. Go to the Database tab and press the "Restore" button. Then select the blueprints.zip file.
You've raised a good point, though. Being able to dynamically position tables would be pretty cool.