Just clarifying for the OP.....Illuminations is a show that takes place on the World Showcase lagoon, and consists of music, fireworks, fire, water and lighting effects, and video projected on a globe that floats on the lagoon.
You won't see all, or even most, of Illuminations unless you have a clear line of sight to the lagoon. The Rose & Crown has some seats on a patio that provides this view, and most of the Cantina's seating has a decent view.
If you're outside of Epcot, the most you'll see is a few of the highest fireworks. These can be seen from some areas at the Boardwalk, but I don't believe you'll see much of anything from inside any of the BW restaurants.
DTD is a few miles away from Epcot; you won't see anything from there.