Currently, you get to pick from the "Hotel Bucket" which is limited to VGC/GCH guests. So there is "some" priority, but not a guarantee. Book early and you will be fine.
Create a Disneyland.com account, if you don't have one.
Add your VGC reservation to your account (this is new for DLR/VGC, not available previously).
Link your tickets to account.
At 60 days out, book your first Park day, and so on... on a rolling basis.
*You need to view your VGC reservation and click to link on that page to "Make Theme Park Reservations" to access the hotel bucket.
**I noticed the other day our check-out day was not available using the above method for Hotel Bucket. I used the regular Park Reservation link and added our last day that way. Strange.