good class IV might include the north fork of the south platte (bailey) if it's running; slim chance. also, the numbers and royal gorge of the ark (guaranteed flow), slaughterhouse on the roaring fork near aspen (all natural), lower south boulder creek (lsb) near boulder (dam released, good chance), gore canyon (a safe bet), boulder creek above the park (good chance), various sections of the clear creek near golden (good chance), something on the gunnison? not sure. and the upper animas at lower flows, piedra? (kinda doubt it, seems to go early), gore creek, and maybe 10 mile near frisco.
give a holler when your in town.