Welcome, Joyce!
Illuminations: Reflections of Earth is my favorite nighttime spectacular at Walt Disney World Resort. I get chills when I hear its opening strains. I'm so pleased you're planning to include it in your itinerary for your upcoming trip.
There are seats at both
Spice Road Table and
Tokyo Dining that afford a view of Illuminations. However, keep in mind that those seats are limited in number and you may have a bit of an obstructed view. There are a few trees that may get in the way of viewing some of the features that will be presented down near the water.
Spice Road Table has formidable pillars throughout the restaurant. If your seat is near one of these, it may be difficult to see much. There are only a half dozen tables right along the water so if you are hoping to snag one of them, I'd arrive early and let the hostess know you are willing to wait. A 7:30 or 8 pm reservation would likely work well since Illuminations typically starts at 9 pm. (You can verify this with a Times Guide picked up at Epcot or on your My Disney Experience app.)
The seats along the window at Tokyo Dining have the advantage of being inside, and thus air-conditioned. However, there is a balcony between the window seats and the show so there's always the possibility that guests standing on the balcony may obstruct your view.
If seeing Illuminations in all its splendor and detail is important to you, I'd eat at 6:30 or 7 pm and then stroll out to the walkway around World Showcase after concluding your meal. From there you can choose an unobstructed view along the railing so that you don't miss a thing.
Have fun,
Jill