Best real-world useful protection I'd recommend is tinted windows. There are two types of leather, top-coated and raw leather. Real leather will soak up water.
To clean real leather, go easy and use gentle products like Woolite. When using microfiber on real, always have it wet. When drying using microfiber, dab and push, don't rub.
For protection of real leather use any product with a sunscreen. 303 is awesome and all purpose. There are plenty others, but I found them to be too oily. I suppose I could have used less, but I never found a need beyond what 303 provides.
As for top-coated, I wouldn't use anything special. Your just wasting product since it will not soak through down to the real leather underneath. I still just use a wet microfiber cloth and occasionally Woolite.
Nothing beats keeping leather out of the sun though... AKA garage, park in the shade or in a structure or get tinted windows.