I run Panaracer Paselas on two bikes. 38 in front, 35 in back. (Old school steel. 38s don't fit between the chainstays.) Ride up to 35 miles on pavement at 70 psi, drop the pressure to suit, ride the gravel, pump up and ride home. For this, those tires are near perfect. For city riding - also excellent. Not flat proof, but I see very few. The gravel doesn't have to be mild either. @
gugie and about half a dozen other forumites will testify that combination did very, very well crossing the Oregon coast range on gnarly logging roads.