I'm all for repealing the 17th Amendment. I'd let the make-up of the state legislature be the tenure-limiting function. Let their choice of Senator be a factor when voting for state legislators.
-PJ
To make the Senate a more federal institution, I'd like to see Senators take orders directly from the state legislature that named them - like in the German Bundesrat. You know, give the states a real say in federal policy-making.