There are lots of threads about how to try to get a good table at Rose & Crown for this purpose. However, this has become so popular, it has been getting harder and harder to actually be successful in this regard. Thus, my advice always is not to sweat the issue too much. There are numerous great places around the lagoon to watch Illuminations. You can have dinner anywhere and then set up shop at one of those places to get a great view of the fireworks.