Definitely include detailed descriptions of the cityscape as he swings. For example, how the lights look from above, the different heights of the buildings. Another great element is the feeling of freedom he gets while swinging.
In a fanfiction, Spider - Man could be swinging during a big festival in the city. There are so many people and lights that it's hard for him to focus. But then he notices some suspicious activity on one of the floats. He has to swing down carefully, without causing panic among the crowd, and figure out what's going on. It could be a new kind of threat that specifically takes advantage of the chaos of the festival.
In the 'Spider - Man Web of Shadows' story, Spider - Man is at the center. His love interest Mary Jane plays a significant role. Other characters include his fellow superheroes. For instance, Luke Cage, who has his own unique abilities and can be a powerful ally or an adversary depending on the situation. Wolverine also makes an appearance. His healing factor and his ferocious fighting style add an interesting dynamic to the story. There are also the villains who are either behind the symbiote invasion or are part of the chaos it causes.
A fanfiction could focus on Black Cat's backstory within the Web of Shadows context. Maybe she has a secret past connection to the symbiotes that is slowly revealed as she battles against them. This would add depth to her character and her role in the story.
In the context of Spider - Man: Web of Shadows' evil ending fanfiction, one interesting aspect could be the character development. If Spider - Man goes down the evil path, how do the other characters react? For example, Mary Jane might be horrified and try to bring him back to the good side. Also, villains might either team up with this new, evil Spider - Man or see him as a threat to their own plans.