Damn you’re lucky. I’ll offer layout advice here. I see some great opportunities. First, create a small utility closet for the mechanical systems (I assume that is a water heater and maybe a space heater? Hard to tell.) Then I would consider a wall across the front, parallel to the garage doors, to create a storage area accessible from the driveway. Make it like 7 or 8 feet deep and the full 30 feet wide. Perfect for yard equipment, car related stuff or whatever else. This would leave you with a music room at around 23 x 26 with direct access from your laundry room vestibule. That new wall would serve as a buffer from the garage doors which would be nice, offering the opportunity to have an insulated wall there for thermal benefits (and for sound containment if that is an issue for neighbors.) Going further, you might put in a storage closet to help refine the room dimensions a bit more, getting a more rectangular space. That could be for gear/accessories/media storage and a record cleaning setup, or whatever you want. Drywall ceiling for sure. Lots of power outlets by the equipment of course.

When/if you do the walls/ceiling, try to make it so none of them are 100% perpendicular with another surface.