1. The link below is a list of all CSU Yard & Garden Publications. Look for those that are either "native" or "xeriscape". These lists of plants have the best survivability in drought-type conditions and are adapted to our Front Range landscapes. Familiarize yourself with the different plants and identify what you like:
https://extension.colostate.edu/topic-areas/yard-garden/?target=publications
https://extension.colostate.edu/docs/pubs/native/FrontRange.pdf

2. When you refer to 'grasses', that could mean ornamental grasses, or it could also mean turf grasses (lawn) that are native and/or drought tolerant. Since I'm not sure which you refer to, here are links to both:
https://extension.colostate.edu/topic-areas/yard-garden/ornamental-grasses-7-232/
https://cmg.extension.colostate.edu/gardening-resources/online-garden-publications/lawns/ - look at the section called: Species Selection

3. Finally, it is VERY important to work with a reputable landscape designer. In a recent CSU publication, it was noted that: the aesthetics of neighborhoods change when lawns are replaced with poorly designed landscapes. A good landscape designer can use a mixture of drought tolerant native or xeriscape plants and still include drought tolerant turfgrass in places where it makes sense and for the best aesthetics. Designers can be found here:
https://www.aslacolorado.org/landscape-architects-resources/find-a-landscape-architect/