Green Mountain West Trail is easy-moderate level hike in Boulder Open Space. I went in March, and since there was little snow, it was easy to navigate and not very muddy. It was not very crowded when I went, but given its location, it's likely a popular trail.
The drive from downtown Boulder was about 30 minutes, and very easy to find. We passed several trail-heads on the way, which offered some limited parking. For this spot, we parked along the side of the road with no trouble. The trail is short, about 2.7 miles long, and takes you up to a peak with a view you don't want to miss.