"Wannabe rock stars and serious fans" get their groove on at this "detail-oriented" Seattle Center tribute to American popular music, including jazz, rock and blues; a high-tech Sound Lab where visitors can let loose on musical instruments is the top draw, but there are also "excellent" exhibits and "tons of memorabilia"; the only discordant note: some find Frank Gehry's building a "psychedelic" "masterpiece", while others opine it's just plain "ugly."