I like Coppertone Sport spf-70. It doesn't sweat off as easily as others, so I don't end up with it in my eyes. I carry a little Nalgene squeeze bottle of it in my handlebar bag so I can goop up every couple of control stops.
Being chrome bald, I wear either a cap or other helmet liner so I don't burn my dome. If it's crazy hot and sunny, I've taken a cue from another guy in our club and I wear a bandana to cover my neck.