My ideal preference would be to amend the Constitution so all the Supreme Court judges are directly elected by the people through contested elections with other judges (they wouldn't be elected nationwide like Presidents, they'd be elected regionally by blocs of states. Right now there are 11 federal judicial circuits. Cut it down to 9 and we have our 9 election districts for the Supreme Court). It would ensure geographic balance on the court and make it unlikely another David Souter would ever sneak unto the court. That's the method used in Illinois and I believe 7 other states for their state Supreme Court.
(Take that, you "democracy is bad, we should let politicians appoint whoever they want for life because they're so much smarter that us" freepers. ;-p Of course, Rick Perry thinks it's BAD to amend the constitution so voters instead of politicians choose the Senate, but GOOD to amend the constitution so voters instead of politicians pick the Supreme Court. Can you say Schizo?)
That being said, going from an appointment-for-life supreme court to a directly elected to serve a certain term Supreme Court is unlikely to ever become law (sorry, Rick Perry), so we'd probably end up with a compromise where the President continues to appoint whoever he wants for life, subject to Senate confirmation, but voters are allowed to review that appointment every 10 years or so for judicial retention, and could deny a Supreme Court justice more time on the court by majority vote. I could live with that. Too bad there's no serious effort to implement such a reform.
BTW, we FINALLY have a Republican candidate for the Illinois Supreme Court running for one of the three Cook County seats on the court this year. He won't win, but at least those of us in the minority can can a protest vote against the socialist Chicago RAT judge nominated for the Illinois Supreme Court.
Here's the existing federal judical circuits so you get an idea of where the elected judges would be running (the D.C. district and the federal district wouldn't get representation on SCOTUS, of course. I don't mind that, I'm glad the folks that elected Marion Barry don't have Senators, either)
We'd have to tweak this map quite a bit in some places (9 is way too big and is run by insane liberal judges already) and find a way to either expand the court to 11 members or eliminate two federal districts (I think 1 and 2 could merged to create a New England district) but you get a good idea. At least five districts: 4, 5, 8, 10 & 11 already look safe Republican and would elect solid conservatives if they started electing judges tomorrow. I wouldn't mind being in the same district with Wisconsin and Indiana, they might help counter the Chicago vote that decides every election for Illinois. Had this been implimented a few years ago, John Paul Stevens would have been up for re-election and he would have been "our" representative on the Supreme Court since he was a Chicago judge before Gerald Ford gave him a promotion. I would have given my right arm to vote against him on a ballot!