But I challenge you to go to someplace like Zum Uerige and drink the
altbier all night and walk away disappointed with your lack of
variety. Or spend a evening drinking nothing but fresh casked
Fuller's ESB or nothing but Augustiner's Edelstoff ... Some of my
favorite places in the world serve just the one beer, and I've been
far from disappointed with sticking with their single offering for
the night.

These world class places and experiences, preceded by dedicated journeys,
are worth their sessions (though if a Munich pub carries a full Ayinger line
I am very tempted to have more than just one of the offerings).

But for every pleasantly-yielding-some-flavor 4% beer that gets reviewed in
a magazine and has a couple of nice notes that gets listed as a good session
beer, I start to wonder who is going to sit down at that kind of session,
without the journey, without the corresponding romantics to drink it
exclusively. The number one "session beer" in the world, in the true
dedication sense, and which its adherents would assert fits the admirable
Lew Bryson definition, is Bud Light. I pub crawl in London and enjoy many
~4% beers and my bladder adjusts accordingly, but since I don't get to
London more than once a year I like to try a whole meandering crawlful in
just one night.

Anyways--great posts Jesskidden & Steve Jackson, and points taken (and I
will hope to take them frequently). :