I haven’t done this particular tour so cant comment on all accommodation you will come across, but the one I did last year covered your Alice Springs/Ayers Rock/Kings Canyon accommodation.
Alice Springs: Rooms were average, with 2 sets of bunk beds in our room (other people had bunks & a double bed) a bathroom & air conditioning. We arrived there about 2pm, chilled out by the pool & then went for a hike up the mountain - recommend that for great views over Alice Springs. Theres no track, just make your own way up. Then walked down to the park pub for dinner. We actually spent 3 nights here (my tour did a loop), & on the last night there is a local guy who brought his reptiles in for us to handle - a python, blue tongued lizard, a couple of dragons & another one that I cant remember the name of. If you do go into town & are not coming back the same time as your roommates, make sure someone has the room key - office staff do not like coming to get you another key after office hours! Found that one out the hard way…
Ayers Rock: Our rooms here were tiny! Again the room I was in had 2 bunk beds & air conditioning. That was it. Bathroom was communal but only a short walk away. Didnt really matter though - you are only here to sleep. & after getting back from viewing Ayers Rock sunset you just want to crash, then you are then up very early (4am) the next morning for sunrise viewing! We ended up turning our air conditioning on & off several times during the night because it got too hot/cold - may not be an issue depending on when you are going - I was there in the middle of summer! There is also a nice viewing spot of Ayers Rock just a short stroll up the hill.
Kings Canyon: Again, average rooms here, 4 share single beds, communal bathrooms but again very close. Bathrooms also had dingo gates - kinda a good idea because you would not want to come across one of those while in the bathroom!!! There was also a pool here too - not flash, looked like a pond but we were so hot from our days hiking that we didnt care! Although dont bother trying to get internet access here - apparantly it was really expensive & the computer wasnt that reliable anyway.
I hope this helps you a bit. Its not 5 star but totally sufficient for what you need. After the long days, all you want to do is crash so really just a place to sleep.
The Northern Territory was great - great home cooked food & awesome atmosphere - hope you have a fantastic time like I did