West of Denver.
Seriouosly, there is plenty of great hunting for both elk and mule deer in Colorado. Lots of factors will enter into narrowing it down, the first of which is your budget. Also your hopes and dreams of what type of hunting you want to do. Guided or do it yourself? Motel, truck camp, or backpack?
Hunting in the mountains can be physically demanding. How good of shape are you in or could you reasonably expect to get in before a hunt? If you are overweight and out of shape and go to a pristine high quality elk area at 12,000 feet, you are bound to have a miserable time.
Like I said, lots of factors to consider before deciding where to go.