Personally we never go to Estes Park any more and I have lived in the Denver area for 55 years and my wife is a native of Golden. But we enjoy RVing on the Western Slope and go into RMNP through the West Entrance every few years.
We stay at the USFS Stillwater campground, with electric, water, and a dump and great lake views. The scenery around Granby, Shadow Mountain, and Grand lakes is gorgeous and the hiking at Monarch Lake can be as short or long as you wish. One trail will even take you overt the Continental Divide to the 4th of July campground. You can rent power boats, canoes, and kayaks in the town of Grand Lake to water ski, fish for trout and kokanee, or just enjoy the mountain views and air. And dinner on the deck at the Grand Lake Lodge can give you a whole new appreciation for sunsets!