I keep my suspension unlocked when street riding as roads in my area are very bad. I wil lock it out before mounting the bike after stopping (say, for red lights) or for climbing steep hills. I believe the loss in effeciency when riding with a suspension at speed over rough roads is inconsequential for recreational riding. As for tires, I keep mine to slightly under (say 2-3 lbs) the max pressure. A higher pressure does give a harsher ride, but the difference in rolling resistance with a lower tire pressure is quite noticeable. You can look for a tire made of a softer compound that will give a smoother ride, though.