The League of Women Voters and an assortment of usually sensible people of all political stripes have recently written in opposing a preferential voting system. I think they're missing the substantial merits of this idea, particularly in comparison to our present system. Their principal objection is that a candidate that is most people's second choice could conceivably win an election. Unfortunately, that happens now, and frequently. How many times have you wanted to support someone like (insert Nader/Jacobsen/Metcalf/ Keyes, depending on your political convictions) but held your nose and voted for your second choice so you wouldn't be helping to elect the bad guy?
I don't know that the rare election of most people's second choice would be all that bad. What is most legislation but a second-choice compromise between parties, or between the Legislature and the governor? What would be wrong with a compromise centrist representative?
Preferential voting would also increase diversity, helping third parties to attain the vote totals that reflect their true constituencies, enabling their candidates a place on future ballots and on the debate stage. It might increase voter turnout: how many voters don't come to the polls because they aren't inspired by either of the two front-runners?
Diversity in politics is a good thing. Alaska could use some original thinking right now. I support preferential voting so we can vote for whom we want, instead of voting against the candidate we don't want.