"At the Stroke of Midnight" by Steranko
I "discovered" Steranko just a few years ago, but "WOW" was a wonderful "discovery". I don't know much about him and I can't say I like some of the early works that look more like Kirby than anything else, but his work on just a few issues of Captain America and this short story (as well as "Red Tide") are nothing short of magical. He used everything from composition to lettering and color to tell his stories and he did it in such a sophisticated manner!
"Temple of the Spider" By Archie Goodwin and Walter Simonson
This just squeaked in just under 12 pages. One of my first great comic book impressions came from reading the Manhunter series that Goodwin and Simonson worked on together. It was one of the few things that DC collected and reprinted back then and that made it very assessable. Wonderful stuff (that got a couple of Eisner Awards for Goodwin and Simonson), but this story (that never got even mentioned for an Eisner) might be better than Manhunter serial. The art is definitely more mature here and Simonson's storytelling is very solid...and of course Goodwin is the master of writing short stories (as he proved during his Creepy and Eerie days).
"Elektra" by Frank Miller (Bizarre Adventures Magazine)
I think that was the first time that I did not just look at the drawings in the panels, but also looked at how the panels were arranged on the page...storyteling, wow! Frank Miller told great stories in Daredevil every month, but this short story was something totally remarkable AND it was a perfect black and white story. I re-read this story before posting about it and I was glad to see that it does not feel dated, unlike some of the earlier Daredevil work. I think it has been colorized and reprinted in a number of collections, but if you have never seen it printed magazine size and you never seen it in black and white, you are missing out.
The images below are from the original pages posted on comicartfans.com...pretty :)