If you aren't up for the 10-12 hour drive to colorado, you might check out some of the stuff in the Ozarks. All the famous Ozark tailwaters (White, Norfork, Little Red, Taneycomo, Beaver) are probably going to be high water this year with all of the rain. You could always hire a guide on one them though. Cold weather and high water usually means big articulated streamers and a chance to catch a trophy brown trout. If you don't want to do that though. there are other options in the area. Missouri has 4 trout parks that are catch and release, flies and lures only during the winter, roaring river, bennett springs, meramec, and montauk state park. These are all closed down during the week and open up on the weekends for fly fishing. These parks routinely cough up some big trout this time of year. If that's not your cup of tea, there are some great rivers in the area that hold wild and/or holdover trout that are fishable year round. The upper north fork, current river, and eleven point river are all great spots. There are also some smaller streams in the area that have wild mccloud strain rainbows if you're looking for some really technical winter time fishing.