I was really excited about "Houses" because I thought it was a live version, but still a cool compilation.

This comment reminded me of something I thought I remembered reading at
Songfacts. (A great site, by the way.)
Here's what the page on "Houses" mentioned:
"Despite being a fan favorite and about their shows, this was never performed live." Interesting stuff, Gina - thanks!
I wonder why they never played it live - Zep certainly varied their setlists considerably throughout their career. I always found it interesting that they didn't release the song until
after the album of the same name was released. I thought Plant's voice was relaxed on this song and that the riff was pretty cool.
Plant varied his voice throughout their career. My favorite Plant vocal style was the rough-edged sound he used on songs like "Trampled Underfoot," "Custard Pie." He countered that with his high-pitch wailing style on "Immigrant Song," "Whole Lotta Love," "Heartbreaker," and "Rock'n'Roll." His third primary style was his clear-as-a-bell approach as in "In the Evening," "Fool in the Rain," "Going to California," and "All My Love."