This right here tells me your concerns are different than most people's. Sunblock isn't really designed to prevent sun tans, but I imagine the highest SPF possible will make them the lightest. Bullfrog and Banana Boat seem to be people's favorite brands. The only other thing you can do is a little bit of sunning without the sunglasses to even things out a bit. I know people who ride with their sleeves and shorts rolled up varying amounts to make a smoother transition. Me? I look like I have a white t-shirt and shorts on all the time