Trial and error my freind,just pick one and hunt it.
From what I hear Colorado has elk behind every tree,way more than we have in Montana,one behind everyother tree here.
If you have been to Colorado befor,go to the area thats closet to where you have been before.If not look for a area that has good cover,decent access,water,food and timber.OR I would look at harvest reports of those area's the area that has a large harvest number,thats where I would head(or that could mean more pepole but at least some elk there).
BBJ