I've stayed at the 4Q once about 5 years ago. Ever since then, I've been at TheD. They have nice clean rooms. I've never been bothered by the AC noise. They look like they're newer units, so they're a bit quieter. One time I did get a really low floor. Like 6 I think. The noise from the stage was a bit loud, but not like I was right next to it. Most of the time, you can hear it, but it's not bad.
Rooms have always been clean. And, I ask for a fridge to keep my drinks in. I've only been in the normal corner king rooms so far.
The main casino isn't loud during the day. But, about the time the dancers come on, they bump it up. 6ish I think? Yes, it stinks that their cafe opens at 8am, but you can charge your meals at DuPairs to your room at TheD, and they're 24/7. And, only about 5 min away. Get the pancakes.

But, they still don't have a unified players card yet.

Come on man. Maybe they're waiting until the remodel LVC?
I've never had to wait in a line checking in, but I normally got there about 2pm, so it wasn't a prime time.
The elevators have gotten better over time. They normally have someone there to help you out during the day. The floors that an elevator are going to are on the side of the door. Just to double check you're in the right one when drunk.
Before you check out, run by the hosts office, and check in with them. It's right beside the check-in counter on the way out the back on the right.
I really like TheD. They've always treated me well. I'm sure you'll have a blast.