We have lucked out on our past two visits to Epcot. We got the latest priority seating at the Rose & Crown pub, around 7:30 I think, and both times got a table on the patio. We timed it so that we were just being served coffee and dessert as Illuminations started. Some of the fireworks go off right in front of you and you can feel the heat. I was the hero to my 3 kids on both occassions. Even if you can't get a table on the patio, the guests inside the restaurant can stand outside when the show starts.
Tammi