A friend used to have good luck after the snow receded a bit on the state and federal land at the head of Horseshoe Creek near Esterbrook and on the state land south of Hoseshoe Creek just off the national forest along the Platte/Converse county lines. Any place with a creek and some pines is likely to have turkeys if you can negotiate the weird access in the area. In the Black Hills I've found walking along ridgetops or driving along roads, calling occasionally on a box call will get answers, then you can maneuver to work the birds.
