While Durango should be relatively snow free the last week of April, as you head north, you will find a lot of snow. Last year, we were shoveling snow off our driveway through late April and we're only at 5900'! The Silverton train won't be running yet, and the streets of Silverton will either be snow packed or mud fests. Still beautiful, but lots of the tourist activities, shops, restaurants, etc. won't be open yet. Some parts of Mesa Verde don't open until mid-May, and Vallecito Reservoir may have a little too much snow to make that drive worthwhile.
As far as your route, you shouldn't have a problem with your rig from Pagosa Spgs. westward on US160. (I missed the fact you were heading into Pagosa from the south, so Wolf Creek Pass isn't an issue.) If you're ultimate destination after Cortez is Flagstaff, we personally like the views on the US 160/US 89 route. All this presumes no unusual late snow.
