I did the half day Browns Canyon rafting tour and highly recommend it! Their staff and guides are friendly and have a great deal of expertise. Our raft was a mix of inexperienced and minimal experience and our guide Jeremy made it look easy to get us safely through the trip, though I'm certain it takes a great deal of skill on the guides' part.
The canyon is truly stunning from start to finish!
This was my first time whitewater rafting and I felt safe the entire time. They also offer wetsuits, booties, splash jackets for anyone that wants to use them. And private areas were available for changing if needed. We also heard from locals that this was the best run company for this kind of adventure.