we stayed at both rims for a couple nights and then backpacked down to phantom ranch and stayed a couple more nights and came back out. if you are luck you can get steak down at the ranch (they mulepack food down)! bright angel creek (i think that’s what it’s called) is a nice cold stream to take a dip into. bright angel was one of the trails we were on.
we did the trip in June and it was hot as hell. we brought a tent with us, but we ended up not using it. Ive heard the scorpions come out at night, but didnt feel any. I recommend going when it’s a little cooler and/or hiking at night/early morning, especially when you are coming out. ;} either way, you’ll have a good time… good scenery, some wildlife, and a good workout.
the trails we were on were crowded at the top of the canyon—with people gathered around the watering holes, but there were long stretches of secluded hiking as you get further down too.
if you are not up for backpacking, I think you can take mules down or even a raft through the canyon on the Colorado. My neighbor has walked to the bottom and back in a day without anything other than food and water, so that might be an option too. any way plan your trip and you will have a good time.