Went yesterday and noticed this place lacked its own thread.
Just before 2pm the place was packed and hoppin'- they were three deep at the bar, and all the tables outside (picnic benches) and in were taken.
We were drifters (though drifters with beer after a short wait in line) for 5-10 minutes, then bench space outside opened up. It's a really lovely place to be on a warm Petaluma spring afternoon, and the music yesterday couldn't be beat- the Central Valley Boys played 2 sets of bluegrass, with the five players circling a lone mic and moving in and out as the tune called for the various instruments to rise to the fore. I really enjoyed the music.
There are several beers on tap one can't find elsewhere- I had Fusion 12, a very creditable double IPA, and and a second, hoppier version of Lagunitas Sucks.
I'd brunched, but my friends' sandwiches looked good, particularly the Reuben with Zoe's pastrami (new meat purveyor to me). They claim to smoke brisket for sandwiches for 20 hours.
Despite the throng, Lagunitas has enough staff that service is prompt, and you won't sit before an empty glass for long. The Mason jar affect for beer presentation is slightly annoying, but the quality of the brews more than makes up for it.
The growlers to go look for all the world like a 40oz Country Club and they bring it to you in a paper bag- not sure whether that's intentional irony or not.
Update on Lagunitas' plot to take over the world here: