This article by George Will is a succinct defense of the Framer's decision to have Senators elected by State Legislatures. Most people do not even know this was originally the case. I would be in favor of repealing of the 17th amendment. I continue to be amazed at the wisdom of the Founders of this great Republic. What they gave us has and is slowly being diluted into a complete Democracy which one of the founders called" mobocracy".
The 17th amendment is one of the reasons that the States have become increasingly subject to the National government. Centralized power always cultivates an environment ripe for tyranny. The Senate was designed to keep part of the legislative power diffused throughout the States. With the adoption of the 17th amendment the States lost their ability to check the National power from overreaching.
I recommend the above article.