Judge Sidney R Thomas, 56, is from Montana. He got his undergrad and law degrees from state universities there. He was in private practice in Billings until he was nominated by Bill Clinton in 1995 to the 9th Circuit Court of Appeals based in CA. His confirmation was delayed for awhile, not because of any issue involving Thomas. A Senator wanted to see the huge area served by the 9th Circuit split up.
He apparently has not said anything in his tenure as a judge to get people riled up about his values.
His time spent as a trial lawyer would distinguish him from most if not all of the current Supreme Court justices.
Some people, including me, believe that Judge Thomas is being considered because of a desire to bring some geographical/educational diversity to the high court. 8 of the 9 graduated from Ivy League law schools. 7 have spent their careers east of the Mississippi River, mostly along the east coast. 2 others claim CA as their homes now, but both went to Harvard.
I am not convinced that these are important factors in choosing a justice but it is probably in the political calculation.