If it's quite cold or if it's very rainy, you will want a tent, and Western River supplies a tent for every two people.
But..., if you're travelling in the summer, it will not be cold. In fact, it may be very warm, and one piece of advice offered to get to sleep in the heat is to take your sheet down to the 50 degree water in the Colorado river, dip it, partially wring it out, and allow it to cool you off and allow you to go to sleep.
For us, the weather was about perfect. Just the sheet when we first went to bed and then the sleeping bag proper sometime in the night when it cools off.
There are almost no bugs, so that's not a problem. And in the high desert, there's very little rain, and what rain they do get pops in and out in about 10 minutes. The very first night right at midnight, we got 5 minutes of rain. We pulled the ground cloth over us for 5 minutes and that was that. Never saw rain again.
In the picture, you'll see the cot, chair, and drying rack supplied us by Western River and nature. Things dried really quickly in the desert.
It's really delightful to sleep in the open air, gazing at the clear sky through the frame of the canyon, hearing the rushing river, and just enjoying the beauty of nature. We did see the occasional shooting star as well.