If your partner enjoys the outdoors, consider packing a picnic for the two of you to share. Instead of going to your local park, head up to the rooftop of your house or apartment building. Lay out a blanket and surprise him with his favorite snacks. If your roof has a flat surface you can hire a musician (or just bring a CD player) to play the song you danced to at your first date, or even your wedding. Spend the evening dancing, reminiscing and stargazing from the roof.
If your sweetheart enjoys sentimental gifts, make her one that's straight from the heart. Build a scrapbook that chronicles your first date, a special vacation or several significant events in your relationship. This could be done in a traditional scrapbook or, if you're adept at using computers, a video montage of your favorite pictures and songs. Leave room at the end to add more memories that you will make in the future.
If your other half is a little more adventurous, inject some spice into your Valentine's Day. Have some boudoir photos taken, either at home or professionally. Frame the photos or arrange them in an album. Seeing sexy photos of you is sure to get your partner in the mood for a night of passion, so offer to model the intimate clothing so he can see how they look "in real life."
If your significant other loves entertainment, whether it be movies, dancing or scoping out the latest venue in town, a fun date-night might be just the ticket for a romantic Valentine's Day. If he's a sports fan, try tickets to the home team's big game. If she loves music, try a concert. Make the night special by taking care of all the arrangements; find a babysitter, pack any clothes or items he will need and even pick him up from work to whisk him away for a romantic evening.
If your sweetie enjoys the more traditional Valentine's Day, tried-and-true gifts like flowers, chocolates, or jewelry may be your best option. To put a romantic spin on these ideas, set up a scavenger hunt with your gift as the prize. This could be done on a large scale, such as your entire community, or on a small scale such as your house. Use both funny and romantic clues like "we had our first kiss here" or "this is where I face-planted trying to impress you with my skateboarding skills."