I support adding a third senator per state for independent reasons, but I would prefer that all three be elected directly by the people, not through state representatives elected in gerrymandered districts.
As for the phase-in of the third senator (irrespective of how he’d be elected), it couldn’t be done the way you say, DJ, since Article V of the Constitution (the one that permits amendments) specifically declares that no amendment may deny a state of equal representation in the Senate without its consent. So every state must elect a third senator at once, and the phase-in must be done the way that it was done for the 1st Congress—by making the initial term for the new senators 2, 4 or 6 years so that each class has the same number of senators and no state has more than one seat up the same year. So if the election for the third senator is in 2014, FL would elect a senator for 6 years (its current senators are up in 2016 and 2018), GA would elect a senator to an initial 4-year term (its current senators are up in 2014 and 2016), and RI would elect one to an initial 2-year term (its senators are up in 2014 and 2018).
Though many would balk at adding more seats to Congress I’d like 3 Senators as well. 1 Senator from each state in each cycle, nice and even.
Also expand the House a little bit. Especially if we ever do add PR as the 51st.