My good friend and Ohio blogger Brian at Repeal the Seventeenth Amendment writes an interesting analysis of how Congressional "lame duck" sessions work, paying particular attention to the ambitious agenda pursued by the lame duck session of the last Congress. He points to Progressivism as the engine that made such a session possible, in contrast to past practice, in which ethical considerations generally made such sessions relatively inactive.
There is another interesting point that Brian did not explicitly mention: Repealing the Seventeenth Amendment would reduce the motivation for aggressive action during the lame duck sessions. Senators, while limited to six-year terms, served essentially at the pleasure of their state legislatures. Since they were not directly accountable to the people, they knew they (or their successors) would still have to consider the interests of their state. Therefore, the changes from one election to the next at the Senatorial level would be less pronounced. Items that the House pushed through in the heat of passion would surely be delayed or at least given more sober consideration by the Senate.
Lame duck sessions expose the downside of democracy. Having a Senate that is elected by the state legislatures is admittedly undemocratic, but paradoxically is better able to preserve free government. I think this is a good tradeoff.