One cargo van and one driver. Your freight is picked up in Colorado and driven straight to the dock in the other state, with no terminal and no transfer on the way.
All year: east and south, where the interstates stay low. Kansas, Nebraska, Oklahoma and the Texas panhandle.
Spring to fall: Wyoming, New Mexico and Utah as well. In winter those runs mean crossing high passes, and the van stays off them.
A run that goes out and comes back with a load is the best kind. If you have freight heading back toward Colorado, say so when you call.
The van is rated under 10,001 lbs, so it runs without the federal hours-of-service clock that parks a big truck for ten hours. Rest stops are planned around your deadline, and you get a realistic arrival time before the van leaves. See what fits in the van.
A store that sells new merchandise to a buyer in another state can book the van to deliver it. The store books and pays, not the buyer. More on retail deliveries.
Send the pickup, the drop and the deadline. You'll get a price and an honest read on the timing.