This album comes out of my collection and onto my CD player or iPod playlist every few years, and it never disappoints.  Of the three early-70s primarily instrumental albums, "The Grand Wazoo" features the biggest band and perhaps the most relaxed sound.  Unlike other Zappa albums, this one is almost gimmick-free.  Everything you hear on it seems to have been put there purely for musical value.  The one song with lyrics, "For Calvin" does have some distorted and exaggerated vocal stylings, but as is sometimes the case with Zappa, they work beautifully here.  Elsewhere, you'll hear some fantastic guitar work from Zappa, incredible electric piano work from George Duke, lots of fabulous horns especially Sal Marquez on trumpet.  There is a merry sense of humor throughout much of this record, but there's a rare, for Zappa, lightness about it.  No rants, no Brechtian confrontations, no strained nods to Varese -- just purely original, enjoyable music.