I exercise, read, etc but nothing that's a real hobby, so do I just leave it blank?
What do you read? What kind of exercise do you do? You might be able to make the answer sound a little more interesting - "I do cross-training and am studying the classics," or "I work out and read historical fiction," or whatever, sounds more interesting than "I read and exercise."
Do you ever travel with your family? Even within your general area?
Watch movies?
Spending time with family, as has been noted, is also a perfectly fine response although I'd leave that one less specific to avoid awkward questions.
This question serves two main purposes:
1. Help the admissions committee avoid recruiting people who are so boring that they have no spare-time activities at all, so ADHD that they'll have no time for work, or so addicted to adrenaline that they're constantly going to be hurting themselves
2. Conversation starter on interviews
Clearly #1 isn't a concern here. With #2 in mind, put things you wouldn't mind discussing with an interviewer. It's a nice way to put a human face on the application.
