My daughter had hers out this past summer a week after she turned six. She did end up staying overnight one night, but not because of anything age related. She had vomited, wasn't eating or drinking, and was really lethargic as a result. There are certain "tests" the kids have to pass to get discharged, and drinking enough fluids in a certain time period is one. They also have to be urinating. The procedure itself was way faster than I thought it would be... I got a coffee and was texting some friends and the doctor was standing in front of me to say it was done! My daughter didn't need her adenoids out after all, just the tonsils, which came out easily given that she had had strep for about 6 months straight at that point. It was very necessary.
Recovery was harder than I thought but worse in the hospital than at home because she just didn't feel good and was in a good deal of pain. Once we got home, I literally sat with her for two days and forced her to drink as much as possible. By four-five days post surgery, she was doing better, drinking more, and in less pain. We kept up with the Tylenol for almost the full two weeks' recovery, though! They were right when they said it was an up and down recovery. She'd be fine, then suddenly say her throat hurt again. She also slept much later in the morning the first week after surgery.
One thing i was NOT prepared for was my newly turned four year old daughter's reaction to all of this. She was upset that her sister was in the hospital for a night, and very worried about all the people coming and going and being stressed. My husband and I tried to make it as smooth for her as possible, but she did get very clingy for the rest of the summer. It was fine with me, to help her and comfort her, but I just wasn't expecting her to feel it so deeply. You just never know! So take help if you can get it and hopefully your other kids will cooperate with the help. Good luck! We are so glad we did it, no more strep all the time, snoring, and just generally not feeling well for my daughter since she got rid of the tonsils! What an improvement!