Specific to Black Rock: yes, the parking is usually full, b/c there's not much of it. It's located in the Sheraton's parking structure. I think there are 10 or 12 spaces, and at least two are reserved for handicapped parking.
Just park at Whalers Village, and buy something at the ABC for the validation. It's a longer walk down to Black Rock, but you won't spend time waiting for a parking place.