If you want the luxury of having a seat while watching Illuminations, you should be prepared to eat jellied eels and kidney pie!
Just kidding of course. AFAIK the only other dining option with an Illuminations view is the counter service place at Mexico, the Cantina de San Angel. But since that has open seating and is not "gated" like Rose and Crown, you'd better be prepared to defend your spot.
I think there are one or two other locations where seating is available, but they are reserved and not open to the general public. If you are fortunate enough to participate in an Illuminations Dessert Party or something similar, you may have seating. Another option is an Illuminations Cruise, but those are very popular and difficult to reserve.