Gavin and his friend Brian plan a surprise visit to see Piper. They book a last-minute flight to Atlanta, Georgia, and try to locate Piper using her Instagram stories. After multiple attempts and investigating different locations, they finally find Piper's apartment building and then spot her in a nearby park. They split up to cover more ground, and eventually, Gavin finds Piper and surprises her.
Here are the key facts extracted from the text:
1. Gavin and Brian were filming a video and decided to book a plane to Georgia to surprise Piper.
2. They booked the flight and arrived at the airport, then boarded a plane to Atlanta.
3. They landed in Atlanta and got some rest at a hotel.
4. The next day, they tried to find Piper by checking her Instagram stories for locations.
5. They found a location from her story, Centennial Olympic Park, and went there to search for her.
6. They didn't find her at the park, so they decided to wait and see if she posts another story.
7. She posted another story, but it was just a view of the city, which didn't help them locate her.
8. They decided to look up places in Atlanta and found the Weston, which they thought might be a good lead.
9. They went to the Weston and asked someone if they had seen Piper, but they didn't find her.
10. They saw a girl who looked like Piper, but it wasn't her.
11. They decided to split up and cover more ground to try to find her.
12. They eventually found Piper and surprised her.
Note that some parts of the text are unclear or incomplete, but I've tried to extract the most relevant and concrete facts.