We've stayed at both the Anaheim Hilton and the Anaheim Marriott. Must say that the Anaheim Marriott is by far the more luxury hotel than the Hilton. Marriott rooms were just nicer and updated, with very comfortable bedding and nice sized bathrooms. Just an absolutely nice hotel to go back to after a day at Disney. And the price at $110 is very good for the Marriott.
Our experience at the Hilton was not great. Hilton standard rooms (probably what you'll be given at a conference rate) seemed to be of lesser quality than those standard rooms at the Marriott. Our Hilton room was of '80s decor and the beds were old and indented, and we found lots of dirt/stains on the floor. Our bathroom (especially the tiles) had brown grout and brown liquid on the floor, the air vent dripped water, and the bathrooms were also so small that it was hard to squeeze 2 adults/children in there at the same time (and I'm not a big person, just 5'1" and 100lb). I asked Front Desk if we could switch rooms as we thought our room was dirty, and they informed us that "all rooms were the same". Hmmm, I guess that meant "no". We were impressed with the Hilton lobby, public areas, and dining selections, which lured us into this hotel in the first place...but the rooms and the customer service really disappointed us.