There is the traditional way of flowers, with candy. With a red and pink color theme. But I think to truly impress someone.. perhaps take her out to eat somewhere with good food? With wine and candles. Maybe incense too.
Alternatively, there's always the beach. Perhaps right at the time during sunset, when the sky is a bit reddish-orange before nightfall. Or if travel isn't a problem, maybe somewhere like the Grand Canyon, Mt. Fuji, Colorado mountain country, Greece, Italy, or even Paris.