Golden is a beautiful town just 30 minutes south of Boulder, with a bunch of great restaurants and a cute park to sit next to with a river running through. This is where Colorado School of Mines is located, and also Coors Brewery. Attached in the link to schedule a tour while your here!!
Rocky Mountain National Park is Located in Estes Park North of Boulder. It is about an hour drive from Boulder, however this has the some of the most stunning views of Colorado. I would recommend doing the Trail Ridge Road to the top of a mountain at 12,183 feet. Jake and I came here on our first vacation together and saw a ton of Elk, bear, moose, and wildflowers. It will not disappoint!
When you first drive into Boulder you will see on your left the beautiful Flat Irons. There are a ton of hikes to see amazing views! Linked is a website with directions and information to a couple easier hikes. If you have not been to Colorado before, or to a higher elevations, I would recommended to start with an easy hike and drink lots of water!
Denver is only 30 min away from Boulder, which is the capital of Colorado!! There are so many places to grab something to eat, walk around and enjoy the city. Union station is very cool to see, which is right next to Coors Field where the Colorado Rockies play. The Dairy Block on Wazee St is also new to Denver with bars, restaurants, boutiques and a nice place to walk around. Little Man's Ice cream is also a hot spot to hit right outside of Denver with delicious ice cream and shakes.