I believe there are.
But let us start with an analysis of the current system. What is wrong, and why?
Non-competitive elections for important positions because there are too many higher offices and too few lower seats. Also, inactivity is an issue, but that is cured by sparking interest and hasn't seemed to be much of a problem of late.
Really, regional legislatures, simply to create more avenues for new members to learn and participate are the best solution to it all. They tend to serve as refining mills and launching pads for new members to gain prominence and eventually fun for higher office. So the next question is how can a federal amendment spur the formation of regional legislatures. That's what needs to be answered.
Oh great, even more uncompetitive elections.