Hi everyone!
I was accepted a few days ago, and I’m now starting to consider my housing options… I want an all freshman dorm and I’m considering Wilbur and Stern. If any current/past Stanford students could help out & give advice it’d be super helpful 
You may request an all freshman dorm or a four class dorm. You may not request a specific dorm or complex (such as Stern or Wilbur).
You get to rank your preferences for dorm types; as fredthered says you don’t get to choose a specific dorm in most cases (exceptions being ethnic theme houses such as Ujamaa or Casa Zapata).
can we request a roommate?
@schakrab No you cannot. All roommates are hand-picked, but you do not get to request one nor do you find out your roommate until move-in day!
After freshman year you do get to choose your roommate (if you want to). Your freshman roommate is based off of responses to a bunch of survey questions (when you go to sleep, how loud you like the room, how social). It helps lessen the otherwise inevitable pre-college judgement of determining if people you’ve never met should be your roommate.
As other posters have said, you request dorm type not specific dorms. All freshmen dorms tend to be the more popular choices and are usually seen as more social/louder. Wilbur and Stern are pretty similar. Personally I think Wilbur dining has better food (definitely a better brunch!) but you can eat at any dining hall and Wilbur/Stern are right across the street from each other. The atmosphere of dorms within Wilbur and Stern (Donner, Zapata, Burbank, etc.) vary year-to-year although some do have specific themed programs.