What does she like to do? If going to the spa is something she enjoys but doesn't get to do much, then that could be a good idea. If she likes the outdoors, maybe plan a hike at a state park you haven't been to before. If you can cook, plan a homemade meal of her favorites. See if there's any free/cheap events in your area that weekend that she might like. Find a local art exhibit, concert, etc. Find something that she likes but doesn't often have the time for, and make the time by making it a gift.