For Wyoming, Tailwaters are generally the best fishing that time of year.

North Platte around Miracle mile or Grey Reef fish ok with streamers, san juan worms from most fishing reports I've seen.

Wind River, also fishes well that time of year, but a reservation permit is needed for that water.

Depending on altitude, may run into ice conditions. If looking for still waters, many of the reservoirs fish ok during that time period that are in the "lowlands" (Boysen, Alcova)

Yellowstone Park is closed to fishing until Memorial weekend.

Good luck!!

Paul