I would send an invitation or Valentine flyer made on the computer and set the time from 2-4 or 3-5 and say for cocktails and hors-d-veures (sp?). Then they won't expect dinner. I too would put flowers in the center of the candles. You can put them in a beautiful vase (glass or silver), and set it on a large, glass mirror with greenery or petals on it. I would probably use roses - romantic. I too would put a red plastic table cloth under my lace cloth if you can see through it. I would probably make 15-20 different kinds of foods for that crowd. I would think you might have 50-80 people out of a 100.
You can also make dainty cookies, bars or the small 'cherry blossom' cheesecakes would go with everything else. Meatballs with pineapple or cocktail weiners are a good item. Smaller Crepes would be nice -- meat, vegetable, or desert.
The spinach balls that I posted a long time ago are great and a couple of large cheese balls would be nice with about 4 dips with crackers.

I would probably make a red margarita punch in a punch bowl and serve a non-alcoholic punch in another punch bowl and coffee.

Have fun
Linda B