Find a dark, romantic bistro with great coffees and desserts, or an independent book store that encourages browsing. Find a rarely-used corner deep in the stacks of your library. Blow the dust off some musty old volume and read it aloud together. Steal a few hot kisses. Pretend you've just won the lottery.
Test drive a sports car together.
Browse a ritzy museum gift shop or art gallery. Drive along the outer borders of your city or county, exploring new neighborhoods and villages where you've never been. Ride a city's entire public rail transit system, going out on remote branch lines, just for the heck of it. Spend the whole evening dressed and acting as characters from a play, movie, or book that you both enjoyed. Speak only gibberish and let your thoughts be understood from your emotions, gestures, and tone.