Perfect date night itinerary:
Depending on how adventurous you are, and how much time you have, I would book a table at bluezoo at the Dolphin, then drive to the Dolphin, park the car and dine there. Chances are pretty good that you can get a table there last minute. While California Grill may fit the bill on all accounts, it may be hard to get in. For my money, bluezoo is the best meal on property that you can get with the least advance notice or effort. And since you are not on a meal plan, it does not matter that this place doesn't take the plan.
Next, take a cab from the Dolphin to the Contemporary. (Or if the buses are running regularly, hop a bus to the MK, then walk (or monorail) from there to your next stop). See if you can get in to the bar area of the California Grill for a glass of wine or cocktail, and enjoy your drink(s) until it is time for the fireworks. If you cannot get in to the CG, then I would head to the fourth floor balcony viewing area and watch the fireworks from there. Alternatively, if you get shut out at the CG, or would prefer something else, you could hop on the monorail from the Contemporary and get off at the Poly or Grand Floridian. If at the Poly, head out to the pool area where there is a bar and great fireworks viewing. If at the GF, go to Mizner's for a cocktail and watch the fireworks from the shore there. Whichever place you go, when you are done, make your way to the Magic Kingdom bus depot (walk if you are at Contemporary, or take monorail if you are at Poly or GF). At the depot, catch the bus to the Swan/Dolphin and head back to where you started and pick up your car. If you still have time (depending on how late you want to stay out), you could stroll the Boardwalk for a bit. Maybe grab an ice cream or something while you walk hand-in-hand around the promenade.
Pretty much a perfect date in my book.
