The January 31 Tacoma News-Tribune has this op-ed by John S. Mills, explaining that the Washington state top-two system has given voters greatly restricted choice in Washington state general elections. Mills focuses on the disappearance of minor party candidates from the November ballot.
Although his op-ed does not say so, minor party or independent candidates appeared on the November ballot in Washington state for Congress, or statewide office, or both, in all elections from statehood in 1890 through 2006. But when Washington switched to the top-two system, minor parties ceased appearing on the November ballot, except for President (top-two systems never apply to presidential elections), and except for a handful of legislative races in which only one major party member ran. Thanks to Will Baker for the link.