@BDP24 – fantastic post idea!
I had a similar experience the first time I saw Los Lobos in 1983. Robert Cray was then king of the West Coast blues circuit, but on this night in Portland, OR he was headlining the Key Largo, not a blues bar (saw the great Emily Remler there on another occasion). One of the pre-concert rumors was that Los Lobos included the son of Garth Hudson. They had to have meant David Hidalgo, who kept soloing on different instruments throughout their set.
When Gram Parsons died with an album in the can, the studio needed to do something to reclaim the situation. They put together a hot studio band, recorded an album featuring Gram’s backup singer, and got them a slot opening for solo guitarist extraordinaire Leo Kottke on tour (late ’74 or early ’75?). We were front row center, and didn’t even know there was an opener until we saw the stage set up for a band! The evening ended up being truly life-changing from the moment the young Emmylou Harris walked onstage and literally stunned the audience.
Many years later, I saw an interview of Leo where he talked briefly about this tour. On later dates, Emmylou joined Leo onstage to sing some harmony vocals. Leo was flat-out amazed.
“I don’t sing in tune. How can you harmonize with me?”
“I sing halfway between where you’re singing and where you should be.”
Some other special opening acts:
Stevie Wonder opening for The Rolling Stones in 1972 - as mentioned several times by others
Bonnie Raitt opening for John Prine in 1973 - my first live "Angel from Montgomery", done as a duo with the author & Bonnie Raitt
Marshall Tucker opening for Charlie Daniels Band & The Allman Brothers in 1973 - the MTB seemingly owned the Santa Monica Civic for good stretch of the 70s
The Band opening for Bob Dylan in 1974 - first time seeing my all-time favorite group
Jackson Browne/David Lindley acoustic duo opening for Bonnie Raitt in 1975 - just before the Running on Empty tour, when Bonnie opened & Jackson had a kick-ass band featuring Lindley
Roy Buchanan opening for Robert Cray, Albert Collins & Freddy King in 1984? - Roy could do anything that could be done on an electric guitar