How does the juxtaposition of the description of the Salinas valley and the bunkhouse contribute to Of Mice and Men & support themes/message?

In Chapter 1 Of Mice and Men, the
Salinas River Valley is a Garden of Eden, pristine, green, idyllic for sleeping under
the stars.  It is a place of freedom and natural wonder.  There, the American Dream
seems possible.  George and Lennie are lords of
creation.

However, it also a place for animals.  Lennie
threatens to run off and live in a cave like a bear.  He laps the water up with his huge
paws.  And, in the end, he will be put down on its river bank like a horse.  In short,
the river valley is the secret world only George and Lennie know about, but ultimately
unlivable, like the American dream.  It is a fantasy, a place only to camp, a future
scene of Lennie's mercy killing.

The bunkhouse, however, is
a place where men compete over things: women, jobs, bragging rights.  When Candy shows
George and Lennie around, they find the place crawling with bugs (lice).  It's infested,
unnatural.  It will also be a place of violence, where Lenny crushes Curley's hand and
where Carlson takes Candy's dog to be
shot.

Notice: only one location, the
bunkhouse, is meant for human dwelling, and its accommodations are awful.
 The animals in the barn live better.  The rest of the locations in the novel are more
or less for animals (barn, river valley).  So, both the river valley and the bunkhouse
support the theme of animalistic violence and the impossibility of the American
dream.