For compensating salespeople you want percentages that produce $25-40 in upfront commission and something that produces residual commission where someone could feasibly build up to about $300-$500 in monthly residual commission (if they are full time employees for 6-8 months at a min) is what's you'll be aiming for. This will help you RETAIN you best sales people as they get better and better.
For example if your staff closes a new sale and gets a new member for a $100 / month membership it would be smart to give them a commission that pays them $25-$40 one-time upfront and then $2.00 - $5.00 in recurring commission each month for that member for as long as the member stays on. This gets your sales people to not only care about getting NEW sales but also having financial interest in the clients they have already BROUGHT on.
It's certainly possible for it to be less than that if it's a head coach that's getting a lot of compensation from other means in the studio. However, it's best to have employees in key roles be compensated primarily on the growth of the business. So, minimum wage + a commission structure that pays them based on the number of members they bring on AND retain.
You want as much of their energy, and the flow of their compensation in return, aligned with the growth of the facility's revenue as possible.
Also for the physical space you can have a desk with a computer and then almost a cubicle type setup too if that will work, you want to make sure the sales space is away from the flow of walking traffic as much as possible. Less distractions = more sales.