Which part of Colo. are you going to. There are two large public lands, one in the N.E. corner of the state and the other is in the S.E. corner of the state.
Priarie dogs live primarily in the open pastures/grasslands. They usually won't live in ag. ground because of the fact that the land gets tilled, and that deter's them. They will reside in hay fields such as alfalfa, and are really a nuissance to the farmers when they put up the hay.

If you're making a trip only to target priarie dogs, then WY. would be a much better choice. BUT if you're coming to Colo. to visit relatives, then you should be able to find some targets.

When are you coming? I might be able to show you some targets, if my schedule works out with yours.