We love RMNP and hope you get the chance to explore it while you are in Estes Park. Nathan took Emily here on one of their first dates and almost got them stuck in the middle of a nasty fall storm at 14k feet! The park has something to offer for everyone, including hiking, fishing, camping, horseback riding, or even just driving and taking in the beautiful mountain views. Some of the popular hikes from Estes Park include: Emerald Lake, Sky Pond, Loch Lake, Alberta Falls, Bridal Veil Falls, and Flattop Mountain. You can find lots of info on the hikes at Alltrails. (https://www.alltrails.com/parks/us/colorado/rocky-mountain-national-park)
Fly fishing!
For those that appreciate good views but don't enjoy hiking to reach them, the Estes Park Aerial Tramway is a good option. It's open from 9am - 6pm, and costs $14 roundtrip
About a 45 minute drive to Estes Park, it is a great stop on your way up or on your way home! Walking around the Pearl St. mall has great shopping, restaurants and entertainment. There is also great hiking to get arial views of the city up Flagstaff Road and Mt. Sanitas trails.
One of Emily's favorite bike rides, it is a beautiful fall drive with historic sites and quaint towns along the way.
If you want to visit Denver while in town, we recommend exploring around Union Station, right in the heart of Denver.