I think you had the right idea when asking about a quality cleaner wax.
I would buy a quality cleaner wax to use a few times a year and top the paint with a dedicated wax of your choice or dedicated paint sealant. (I like Jescar PowerLock+ or Carpro Reload). With AIO/cleaner waxes you can quickly clean, polish, and protect the paint and keep all of your cars looking great year around.
Coatings are definitely a great option but to coat 3 vehicles you'll have to be willing to dedicate several days if not an entire week to polishing your vehicles to perfection, prepping for coating application, then applying the coating. Then you'll have to invest in coating maintenance products such as coating boosters, car soaps and rinseless washes that are specifically engineered for use with coatings. You'll also have to make sure your wash techniques are dialed in and you've invested in quality microfiber towels.
If you decide to go with a cleaner wax, Bob provided a great list of recommendations.
Personally, I LOVE HD Speed and Blackfire One Step. They are both truly amazing. HD Speed is the best economical option and Blackfire One Step is the best AIO/cleaner wax on the market right now. Good luck!