We've done all these routes over the years, many times. The "easiest" route is I-25 south, then 160 across southern CO - fewer mountains to climb, but scenic.
However, you also have two more choices.
1) If you leave Denver taking I-470 west, then turn up to highway 285, it will take you down to 160. The climb out of Denver can be slow this way, with some long stretches of 2-lane road with few opportunities for others to pass. We refer to this as the "high plains route".
2) Another alternative is to take I-25 south to Colorado Springs, then highway 24 up into the mountains, which will connect to 285, then take you south. Highway 24 is a 4-lane road until you get to the top, near Divide, CO. Easy drive, scenic country.
If you're just interested in "getting there", then I'd recommend I-25 south to 160. Fewer steep passes, if that is a concern. If you want to see the mountains, then either of the other routes will take you into some pretty nice places.
We live in Pagosa Springs, 70 miles west of Creede, and will be in Creede in August to see some of the fantastic plays they put on. Also staying at the Mountain Views RV Resort - great place - been there many times.
If you're continuing west on 160, use great care descending Wolf Creek Pass. It's very steep, complete with runaway truck ramps, one sharp hair pin turn, and there are drop offs in places of hundreds of feet. Gear down, stay around 35 mph, and you'll be fine. Your engine brake is your friend...
Enjoy your trip!