Bill Clinton won this state twice so would it be that big of a deal if Hillary won Arizona?
Clinton won it once -- in 1996. Perot may have splintered the conservative-leaning vote that year.
Arizona would seem, except for its older white population, to be similar to Colorado -- which Clinton won but once.
Arizona is a big deal even as one state. Eleven electoral votes is no triviality. Most significantly, if Hillary Clinton can win it in 2016, their could be a Senate seat up for grabs. (I figure that John McCain is approaching the end of the line). Should Democrats flip the areas around Phoenix and Tucson, then such could play a significant role in flipping the House of Representatives in 2016.
Arizona has gone for the Democratic nominee only once since 1948. If it goes D, it's practically the equivalent of Virginia going for Barack Obama. But even if it is close, then Hillary Clinton has about a 54-46 split of the popular vote and the Democrats are getting much the same in the overall House race.