Some conference offer special "twilight tickets" which are only sold through their conference link and are not available anywhere else. Over the past few years, those have gotten pretty expensive, though. We have been traveling to Anaheim yearly. DH has a conference, DD1, DD2, and I do the parks. We used to get a twilight ticket for him but at some point realized that it wasn't much less than a one-day-ticket (at a reduced conference rate, sold through the same link), so we went with that instead. In case he gets out of lectures early that day, it provides us with more flexibility.