Solution!
Okay, everyone, I just got off the phone with Apple support and we figured out why Siri wasn't working for me.
In my work address, I included my office room number (I work at a university, so this is required for proper mail delivery) on one of the "street" fields. Thus my address looked like this:
Street field 1: 3400 xxxxxxxx St.
Street field 2: MH338
City: xxxx
State: IN
ZIP Code: 46xxx
I deleted the MH338 and that did the trick! If any of you who are having this problem have a suite number, room number, or other such thing in one of your street fields, this may be the problem.
Also, to those who say that telling Siri "I work at . . . " will fix the problem, it definitely will not. Siri will respond by showing you the address on a map OR by saying "I cant make changes to your contacts. You can do it in the Contacts app, though." Siri seems to be able to define relationships this way, but not locations that relate to you (that is, your home address, your work address, etc.) For those, Siri seems to rely on information in your contacts.
Ain't new technology fun? ;-)