Micheal,
Are considering dedicating one track as your rental track? If so, then configure that track for the type of rental you want to use. TheScaleAuto/ BRMs are perfectly fine for a new racer. It introduces them to Model Car Racing. Not just slot cars. As mentioned, they aren't the greatest handling units, but then, a Flexi can comes off the track just as quickly for a new driver. Fast and inexperienced trigger fingers work the same way as too slow. Plus, with ScaleAuto and BRM, you probably won't have to adjust track voltage to slow them down.
If someone shows promise, then make a spot decision as to whether to 'promote' them to a faster track with a faster car. The JK Flexi RTRs fit that biil perfectly. They are also reasonably priced and are closer to resembling a Model Race Car. Either or both are great options. Just leave them stock and run races for those stock classes. Not every racer wants or needs Wings to fly.
At that point, a driver has potentially had two different experiences and can make their own decision as to which class to run. Perhaps both, or Thanks...Not my thing.
As a Entertainment business, regardless of the type of car used, one idea is to advertise/promote and sell a monthly event as a Driver's School. Complete with car and controller rental for 2-4 hours depending on the number who signed up. Advertise to local youth oriented groups to get a mix rather than just a specific family or company group. Schedule it with time for video introduction of driving techniques, then practice and finally, a multi-heat race. You may wish to assemble Teams for the heats. Built in marshals. Might even create lifelong friendships from those Team events. Schools do that. This type of event works well in other industries by the way.
Don't forget to include as part of the package, company logo gear, e,g, hat, shirt, or coffee mug. for take home. Award everyone a Driving School Completion Certificate. Suitable for framing, of course. I've still got t-shirts and coffee mugs, gimme hats from different type of company events I attended years ago. I still have friends and contacts all over the world tagged to that gear.I imagine there are manufacturers who will co-op the advertising cost for a reprint of their name/logo somewhere on the gear.
All the best and I certainly hope you are successful.