This is pretty general but so is your question so here goes...
As you probably know Colorado has the highest Elk population of any state. There are lots of 'em and they are spread throughout the western 2/3 of the state. As a rule the farther from the road and the nastier the terrain the less hunters you'll see. No one is going to give you their honey hole. You need to go on the CDOW website and look at the harvest data and etc. for the various units. Then pick some general areas that are primarily public land to start looking. google earth can help you determine the type of terrain, roads, etc... A call to the local warden and biologist will give you more info. Local sporting goods stores and archery clubs are other good sources to check with for specific areas. your physical ability, lodging and food preferences, hunting experience, etc.. will have a major impact on how and where you hunt. Its important to be honest with yourself about your abilities. 5 miles back is not the place to figure out you don't know how to use a compass. Also, an Elk is a big critter. Will you have help ? Can you pack one out yourself ? how far ? I could go on and on but these are good places to start. I don't want to discourge by any means. Hunting bull elk in the rut is as good as it gets. I hope you have a great hunt !! GOOD LUCK C.C.