Well, when my kids were younger and loved Thomas the Train. Do the Durango/Silverton train ride up and get seats on the right side. Ride the bus back, trust me.
Hang around the steam engines afterwards when they blow out the steam. Really cool and loud.
We usually stay a couple of nights. The town is cool to walk around in and shop and what not.

Wolf Creek Pass is very pretty depending which way you are coming/going.

Silverton was cold in July, I imaging its very cold in May.