Yes, casino parking is free with a player's card. See the post above with the link to the other thread.
I am an outlier here as I prefer the Doubletree. Yes, the views are not as good and it is a bit farther to walk to the falls and tourist stuff. As diamond, I usually get upgraded to a high floor, so the views are good but not spectacular. The rooms are nice and the continental breakfast is good, but it is not buffet. You order from the waitress. Odd.
I have stayed at the Hilton and the parking situation is a nuisance. I go to the area to work and have to take my tools to the room at night, and it is a bit of a haul from the casino parking to the hotel. The breakfast is good, but when I was there a convention group had taken over everything and those of us that were not with the group ended up in long lines for about everything or were put in out of the way locations. No EL either.
I have not stayed at the ES. It has always been a bit higher than either the Hilton or the Doubletree.