The FDA recently released new guidelines for sunscreen distributors.
SPF 50 will be the max to be put on labels because they found that there is no data that proves sunscreens marked higher than SPF 50 protect you more from the sun's rays than SPF 50. In addition, sunscreens that are SPF 15 or higher are the only ones that can say "they reduce the risk of skin cancer and early skin aging, when used as directed."
Do you use sunscreen daily? I do if I know I'm not going to wear makeup because my Bare Escentuals foundation has a SPF of 15. Any sun protecting product should have a minimum of SPF 15. Lower than that and you're at what the FDA calls a "broad spectrum" and you're not getting a sufficient amount of UVA/UVB protection. My facial sunscreen of choice is Clean & Clear Finishes Mattifying Moisturizer. I have oily skin, so the more matte a product, the happier I'll be.