At every interview I've been at, bringing a spouse to the actual interview day is discouraged. What my husband and I did was during the interview day, he would explore the town and make sure it was a place we wanted to live if I ended up attending the school there. Our thought was that since I will be the one attending school, my opinion of the school matters the most; but, if it came down to deciding between two schools, his opinions about the city he preferred most really come into play there. Some schools host an event the night before the interview day where spouses are more than welcome to attend, or even a breakfast the day of, but as far as I know, it's usually just the candidates who can attend the interview day.