Try to get an ADR at California Grill. It's on the top floor of the Contemporary. A late evening ADR would be ideal so you could watch fireworks while you eat, but if you eat there any time that night, you can return to watch Wishes from the roof. The views if MK are amazing! If you can't get an ADR, we've been successful with walk ups before-- as long as you're willing to wait.
Other romantic things:
Renting a small boat at DTD and touring the Sassagoula River
Segway tour
KTTK tour-- if you're a huge WDW fan
Dinner at Coral Reef Restaurant, San Angel Inn (ambiance), Restaurant Marrakesh (belly dancer)
Trying exotic drinks together in World Showcase
Renting surrey bikes on the Boardwalk
Invent a Disney tradition like a first ride for each trip
Hay ride in FW followed by watching Wishes from FW beach
Carriage ride
Kissing every time someone congratulates you because of your "just married" buttons
Skipping a park morning in favor of "room service"