We had 5 in a room at POR on our last trip. I can't recommend the over-the-door shoe holders enough!!! That was a huge help for keeping all the toiletries organized. I think next time I'll bring a second one to hold everyone's spare pairs of shoes.
Instead of a pop-up hamper, I had a giant washable laundry bag. I took all the clothes down to the laundry and threw the dirty bag in with one load. My bag came out of the wash practically dry, and then it was certainly dry by the time I needed to take the clothes back to the room to fold.
Everyone had their own belt bag with their own stuff in it. We made sure we repacked the bags with necessaries the night before. The bags had sunscreen, lip balm, etc. At night we kept the cameras sitting right next to the belt bags so we couldn't forget them the next morning.
Hat storage for us was a bit of an issue. If we put the hats in the closet, we'd forget to pick them up in the morning. We finally managed to arrange them with the belt bags, but it was a bit precarious on the little table we had. I'll have to figure something out for that for next time.
Next time I will bring more spare envelopes. I had brought a stack to leave for Mousekeeping, but it was also helpful to put receipts in envelopes. We were then able to double check the room charges. Next time I plan to put the food charges in one envelope and merchandise charges in another. It'll save some digging for receipts if we have to return/exchange something (which we did).
One other thing we used that has been a godsend for traveling is a mesh pouch that I hang with suction cups on the back of the shower. It has pockets for everyone's little bottles of shampoo, razors, etc. I also put clothespins in here for hanging swimsuits. I got mine at the Container Store, but I'm sure they're other places too. The shower at POR was big enough that we didn't exactly need this at Disney, but we've used it for every other trip we've taken.
Oh, my kids also had their own little backpack-sized rolling carry-ons that carried all their toys/books/fun stuff. We had a rule that anything they got out of the suitcases had to be put back before bed and before leaving the room. This way none of their "friends" could get lost in the sheets and it kept down the clutter.
Also, before we left I made checklists for EVERYTHING. Yes, this insanity happens when you have a year to plan.

I had checklists for what we wanted in the belt bags for the parks, what to take to the water parks, and a list of everything we packed. My DH thought I was NUTS until we had been at the World for a couple of days and he saw how helpful it was. It also meant we didn't forget anything in the hotel room when we left!
Have fun!