Need advice on options on a remodel

[Allen Phelps]

Hi everyone, I need some advice.   We have an option to purchase a house in the midwest.   The previous owner built a 30x31 room on the back of the house for a train collection.   We need to re-purpose the space.   I would like to hear everyone's opinion on how you would repurpose it.  We were thinking of making it an in-law quarters, a huge game room, or a teenager appt.    I would appreciate any ideas.  Thank you.