For "flower power," I would add the 5th Dimension's "Age of Aquarius/Let the Sunshine In." It's taken from the quintessential flower power cultural demonstration, the 1967 Broadway hit musical Hair: "flowin', blowin', long as I can grow it, my hair ...." It represents everything about the flower power generation with its locus in San Francisco. For "songs of protest," I'd suggest one of my favorites, "Peace Train" (1971) by Cat Stevens. This was not as overt a protest song as, say, Buffalo Springfield's "Stop! Hey, What's That Sound," but Cat Stevens envisioned the end of peace that all the protest songs strove for, as a result, it was sung often at peace rallies and protests.
"Stop! Hey, What's That Sound"
There's battle lines being drawn.Nobody's right, if everybody's wrong.Young people speakin' their minds,getting so much resistance from behind.It's time we stop.Hey, what's that sound?Everybody look what's goin' down.What a field day for the heat,a thousand people in the street.Singing songs an' their carryin' signs,mostly sayin' "Hurray for our side." (Buffalo Springfield)