Rural Upholstery Shops? Definitely trucking companies (and drivers who own their own trucks), movie theaters, gyms, restaurants (especially diners), busses, school auditoriums, doctor's offices, etc.
When we first started out, we printed hundreds of flyers and went to every and any place that may require upholstery repair, handed them out and introduced ourselves. We also placed business cards on cars, trucks, etc that looked like they needed repair.
It took a lot of time, but definitely helped get the word out.