I just want to point this out in case someone gets the wrong idea -- It's not really Candlelight that sells out the hotels, and that is important to note, as I think that a lot of people have a fear about massive crowds for Candlelight that dominate everything throughout the parks, all day long. A lot of the Candlelight viewers can go home at the end of the night, or they stay onsite at a DLR hotel -- and even when they stay onsite, the hotels don't sellout just from Candlelight attendees/crowds (I speak from experience, having been able to get onsite rooms during that time on more than one occasion). The hotels didn't even sell out when the 20 nights of Candlelight were offered -- and promoted more publicly -- in 2012.
In other words, yes, it is an event that affects the crowd patterns in the parks, either by way of crowds coming to see the event, OR crowds trying to avoid the event, but it's not going to infiltrate every aspect of what goes on in the parks (or at the nearby hotels) for the entire weekend. It's not even promoted, and many people still don't know it even exists until they get to DLR and see the set-up.
A lot of people actually clear out on the Monday after Candlelight is over -- I have witnessed it.
The holidays are extremely popular, and we're already inching up to mid-October, so most Good Neighbors would be starting to sell out for early December fairly soon anyway (if not earlier). That's probably not uncommon. Last year the 3 onsite hotels sold out for that same weekend -- but not because of Candlelight alone. It was because there were two other events going on (RaverDay and a nearby pharmacist convention) that involved a lot of the attendees staying onsite.
Also, this year seems to be more crowded anyway (during Halloween Time), and it's certainly not because Disney has added anything new into the Halloween Time line-up in the daytime. I think it's just because of the 60th anniversary. So I would imagine that the 60th anniversary effect will trickle right on through the end of the year in terms of how it affects crowds and hotel bookings during already busy times (like the holidays).