I don't know how old your brother is, but I took my kids when they were 10 and 12. Of course I was VERY nervous about taking them for the same reasons you probably are with your brother-mainly their safety and can they handle the camping for that long? Granted my kids had many river miles and nights before then-but 21 nights? (we did a March trip). I am so glad we did it-it was remarkable bonding time and the canyon is indescribable. Like you, I am ready for a good shower and a good bed by the 5th or 6th night on a river trip, but really life on the canyon became just that life. My family was so into the routine the days just went by. So here is my advice-take your brother, but be prepared as you can to lessen any danger and have him as comfortable as he can. For us that was Dry Suits all the around (remember it was a March trip), good sleeping gear, advanced swimming lessons for the kids and rescue training for us, and a great small group of people. I am confident he will thank you forever!