Garage space. Game room, hot tub. Other??

[Rich French]

Remodeling a 5/3 to turn into a STR. Has a 2 car garage. In the garage are the furnace and hot water heater as well as an electrical panel and emergency generator. Parking is not great on property for such a large house.

Should I keep the garage for parking, there are only enough spots for 3 cars outside the garage. 

Or do I add a game room which is what I’m leaning towards, or put in a large hot tub? Also interested in other ideas. Not looking to sink tons of money into a conversion .