What are the best stretches of Spider-Man comics? These would be periods of ten or more issues when the book is consistently firing on all cylinders. It doesn't necessarily mean every issue is great, but that there's a lot of great stuff in quick succession.
One that comes to mind, and that inspired this thread, is the build-up to Amazing Spider-Man 200, when you had the Death of Spencer Smythe, followed by the Return of the Burglar saga, with the first appearance of the Black Cat, the Kingpin retiring, the return of Mysterio, and the showdown with Uncle Ben's killer.
Roger Stern's entire run of Amazing Spider-Man might also count. You had a key Black Cat story followed by "Nothing Can Stop the Juggernaut" followed by a great Cobra/ Hyde story, followed by the mutated Tarantula epic, followed by the debut of the Hobgoblin, followed by the origin of Vulture, followed by the return of Mary Jane, followed by the return of the Hobgoblin, followed by "The Kid Who Collects Spider-Man" followed by a Hobgoblin showdown.
With Slott likely leaving, it's worth noting the first eleven issues of The Big Time, with the original arc, the death of Marla Madison, "No One Dies" and Torchsong.