If you wish to watch the fireworks at the MK without entering the park there are several choices. Ohana's at the Polynesian and the Calif. Grille at CR both have tables with fireworks views. You cannot be assured of a table with a view however. They pipe the music in and lower the lights.
The beach at the Polynesion is another place to watch. There are one or two observation decks at the CR also.
If you want to see Illuminations at Epcot, you can see the higher up fireworks from the Boardwalk. You could spend the rest of the evening exploring the Boardwalk. Have dinner and maybe go to Jelly Rolls.