Appearances from other Marvel Heroes
While I adore Spider-Man’s rogues gallery and supporting cast of non-powered folks, having characters from other Marvel Comics properties appear makes the Marvel universe feel more lived in and excites fans to see their favorite characters interact. As briefly mentioned before, Ultimate Spider-Man featured a cast that extended beyond the Spidey books with appearances from Silver Sable, Human Torch, Nick Fury, and best of all a boss fight with Wolverine. Spider-Man: Web of Shadows also featured Wolverine as a central character, as well as Luke Cage and Moon Knight.
With appearances of Avengers Tower and Dr. Strange’s Sanctum Sanctorum in Spider-Man’s (2018) pre-release footage, odds of a wider Marvel cast look good. But it isn’t totally clear if the inclusion of these locales is confirmation of these characters appearing or just a fun Easter Egg.