Plan a surprise three-day weekend for your partner. Call his employer and arrange it ahead of time. If working conditions won't allow that, surprise him with a weekend getaway. Make the hotel reservations, and when he gets home from work, have the bags packed and ready to go.
Book a weekend at an upscale hotel and buy tickets for a concert, symphony or ballet. Make reservations at a fancy restaurant. Dress up and do the town!
Enjoy the great outdoors and have a romantic three-day campout with your lover. Fry some freshly caught trout and share a bottle of wine in front of the campfire. Don't forget the marshmallows.
Spend a long weekend at the coast, if you live near enough. Make sure to reserve a room with a fireplace and an ocean view. If it's warm enough, take a walk on the beach. Pack some champagne and scented candles and arrange to have flowers sent to the room.
Pamper yourselves with three days at a resort spa. Bask in a hot tub, get a massage, sit in a sauna, or treat yourselves to a pedicure or facial.
Construct a romantic at-home three-day weekend around a movie theme. Rent several of your favorite romance movies and chill the champagne and treat yourselves to some strawberries dipped in chocolate. Have some fun planning the weekend. To be really creative, take it a step further and dress in costume.