Alternatively, the first time I set a location reminder, Reminders asked me to pick a location to set as "work"- which the app itself remembers.
The problem is, I didn't realize what I was picking when I picked the local mall. Now there's a "work" location default stuck in Reminders that I can't edit or delete, and it's wrong.
Edit: It can be changed under the Setting pane for Mail, Contacts, and Calendars. Under the Contacts section, where my info is asked for, picking my card sets the location to Home. Alternatively, picking a business sets a default location to Work.