The secret surprise getaway

Make an evening or weekend of surprises for her. First you secretly book a hotel that is reasonably close for the night.
Secretly pack an overnight bag with the stuff you want her to wear and all necessities (yours too of course). Hide it in the car trunk.
Tell her you are taking her out to dinner. After the dinner, you surprise her by checking into the hotel. The "party" begins as soon as you enter your room.
Sleep in late and order room service next morning.