Sen. Dianne Feinstein, viewed as one of the few moderate Democrats in an increasingly polarized Senate, is running for re-election in two years, and even Republicans admit she's an overwhelming choice to keep the seat she first won in a 1992 special election. "You can probably call the result of this ... two years in advance,'' said Kevin Spillane, a GOP consultant. "There would have to be an event of 9/11 proportions to make her vulnerable.'' "She's going to be heavily favored,'' agreed Allen Hoffenblum, a Republican consultant whose California Target Book analyzes political races in the state. "I doubt...