John Barrasso is a great choice. Of the three choices, he is the only one that I would vote for in 2008. He is very conservative on most issues, but isn't a party hack like the other two canidates.
BTW the state law that requires the govenor to pick a republican to replace a republican is thought to be unconstitutional by some. Democratic Gov. Dave Freudenthal, class act that he is, did not challenge the law and picked the canidate that will do the best job of representing us and has the best chance of being reelected in 2008.