Come Valentine's Day, a dozen red roses is like a default setting. You can't go too far wrong but you also miss the opportunity for something imaginative, personal, unique. It all comes down to expectations. If you know that's what she expects, by all means, go for it. If you're not sure, here's your opportunity to be a hero.
If you know her favorite flower, you're ahead of the game. If you're married, ask her mother or best friend what kind of flowers she chose for your wedding. Bonus points if you remember on your own.
Consider red roses mixed with other elements like this dramatic arrangement with peonies and sugar cane:
Know her favorite colors? Then just use red as a romantic accent:
Does she dream of the garden she'll one day tend? Choose a few exquisitely fragrant garden roses and a book to feed her imagination and she'll applaud your thoughtfulness.
Or keep the romance going. Give her a special vase and the promise of gorgeous blooms all year long.