I have a B.S. in Professional Aeronautics (ERAU) and am 9 credits away from a M.S. in Aeronautical Science specializing in Aviation/Aerospace Operations. I wanted to stay in my field and build on what I learned during undergrad.

I thought about a management degree (Florida State University) since my employer would have paid of me to go to school part time but I get bored with any kind of management classes so I decided to go with an aeronautical science degree again.

I don't know about Purdue but my online classes are 12-15 weeks long and I take 9 credits a year. In the end a graduate degree is a graduate degree, get one in the field you like and find interesting.