I found an "ibahn conference" (or some such) network in some of the ballrooms in the Marriott, which I'm guessing is their effort to charge $150/day, rather than $13/day, to conference organizers. Luckily, my cellular connection worked fine in most parts of the hotels' public spaces, with registration over in the Sheraton being the biggest exception, so I only had to worry about using Boingo up in the room.