Springtime weather is perfect for going on a day hike with your favorite person. The mornings are still cool, so if you get an early start, you won't get too overheated.
Make sure to pack plenty of water, snacks, sunscreen, a waterproof shell (in case it rains), a fleece jacket (it can get cold and windy on the top of the mountain), a cell phone, a digital camera, and anything else you might want to bring. Pack it all in a lumbar pack and you're all set.
Now where to go? - that is the question. I found this great website - Check out Trail.com. Just type in your state or zip code, and they'll list the best hiking trails in that area. Go out for a day hike and be back in time for an evening BBQ. Sounds like a great way to spend the holiday weekend.