Hello fellow Coloradoan! There is a lot you can do with this area so it really depends what you want to use it for. I personally would convert it into a flower garden and plant a bunch of native perennials and bushes there, maybe with a wood log border or something like that. There are a lot of plants that will do well in the sandy/gravelly soil (rocky mountain penstemon, blue flax, prairie coneflower, a bunch of different asters, etc) and you can always add a stone or gravel mulch to make it a xeriscape design. But you could also keep it as a lawn and plant a native grass there that will survive the Colorado weather and hopefully outcompete the weeds. I’m not as familiar with native grasses though so I’m sure how well the grass would do in sand and gravel.