The Flat Tops are a vast wilderness with multiple trails and access points. I will cover access from Yampa. Take the road to Cold Springs Campground at Stillwater Reservoir. There is a nice short trail north to Smith Lake. For an extensive trail - overnight - take the trail south from Stillwater Reservoir and cut left to Edge Lake once on the Plateau - the hike to the plateau is quite steep. The trail is beautiful and provides access to Flat Top Mountain (12345') - the Flat Top Mountain cairn is depicted in the picture as is Edge Lake in another picture. Be prepared, the weather can change dramatically and with little warning. This is all high altitude hiking above 3000 meters. I hid a bottle of Jack Daniels in a stand of Aspen southeast of Edge Lake in 1997 - it's probably still there.