Don't forget their birthday. That'll keep 'em sweet for that month. Take them away in summer. Shoes go down a treat instead of flowers when you're in the bad books. Don't book them in the fancy hotel / restaraunte to impress them - book them in the first hotel / restaraunte you stayed in and try to get the same tune on the wireless or whatever - the special touches get remembered for years not just months. She will owe you one after that.