Why not somehow integrate sunscreen protection into everyday soap and shampoo? By offering a liquid body soap (or even sink soap) and a shampoo that also provides protection from the sun (ideally SPF 15+), consumers would always be protected (as long as they showered). Also, by including it in the soap and shampoo would also ensure the whole body was protected, including the head and back.
For kids, mixing this protection into their bubble bath or baby liquid soap would also be very valuable to consumers with children. The growing problem of skin cancer and the depletion of the ozone layer will require more innovative thinking to protect our skin.
Though there are many potential issues that might be a challenge (such as ensuring the protection is good for at least 24 hours), this solution would be very well received by today's consumer.