In 1992 all the elements were in place for the Death of Superman to be a monster hit. The market had been primed to accept event comics that regularly sold in multiples of millions. The beating DC took in the early 1990s made the company hungry for a hit and willing to do anything possible to get some attention. The instability of both Marvel and Image in the immediate wake of the latter's initial success made both companies far more vulnerable than their sales dominance might have led observers to believe. To put it bluntly, Marvel had the hot characters but were forced to fall back on the back bench in order to staff the titles in the wake of the Image exodus, and their back bench was not very deep. Image had the hot creators but were pathologically unable to keep shipping dates. (The lack of lasting properties - while certainly a factor in many fans rejection of the creators' post-Marvel output - would prove to be more deleterious to the company's long term health than their short-term fortunes - the people buying up hundreds of copies of Youngblood and Cyberforce undoubtedly believed those characters would be the next X-Men, or at least the next Teen TItans. If the creators had been smarter and more consistent, the characters may well have been; but they weren't and - with the possible exceptions of Spawn and the Savage Dragon - they aren't.)
But for all their demerits in the "cool" department, DC had a decided advantage in the logistical realm. The cover triangles were a concrete example of this: the triangles were a promise that the Superman books would not merely offer an ongoing, serial continuity, but that it would be consistent in both form and content. Considering how many superhero comics and superhero comic companies have floundered for the lack of these basic ingredients, it's something of a wonder they were ever so thoroughly disregarded as they were in the 1990s. It wasn't simply that a story begun in Superman would continue in Adventures of Superman. The situation was essentially such that all the monthly books became a single weekly series. This had its problems, as I have mentioned previously. As the 90s progressed the straitjacket continuity lost its appeal as the stories became less endearing and the titles' lack of individuality became more glaring. But at the time, it was positively fresh. Jim Lee could take two months to put out WildC.A.Ts #2, but if you bought Superman #74 the week it came out then by Crikey Adventures of Superman #497 was going to be in the store next week. There was no "or your money back" promise, but there might as well have been. (I cannot recall if any chapters in the Death / Funeral / Reign sequence shipped late, besides the still-unbelievable and on-purpose three month hiatus between Superman #77 and Adventures #500 - perhaps Mike or another retailer with long memory can verify.)
And, let's be frank: if you were reading comics in the early 90s and you don't have fond memories of breathless anticipation for every week's new installment of the five-month-long Reign of the Supermen serial, then you're a liar. I can't say how well it has held up - I knew even at the time it was little more than extremely frothy pulp fun. But man, they knew exactly what they were doing: everyone I knew wanted to know who the "real" Superman was, who these pretenders were, and how it was all going to shake out. Even by the standards of superhero comics it was preposterous, convoluted, riddled with plot-holes . . . but it was sure a fun ride while it lasted.
I specifically remember driving around to different comic shops in Portland, OR (on a vacation trip, if memory serves me well) trying to track down Superman #82 and Batman #500, which had shipped right next to each other. Both were culminations of year-long storylines, and both were subsequently sold out everywhere I went. Moreover, I remember missing out on Green Lantern #47 when it hit shops and having to track it down by hand over the course of the next couple months. There was no eBay back then: if you missed an issue, best bet was to drive to the next store, and the next store after that.
These stories, more than simply big-selling events, were also uniquely designed as overt criticism of the very comics with which Batman and Superman were now forced to compete. The "new" breed of heroes, folks like X-Force, Youngblood and Spawn, were the target of a concerted attempt on DC's part to prove the continuing relevance of their blue-chip properties. Both Superman and Batman fell in battle, only to be replaced by "better" versions who couldn't cut the mustard. More on this, as you can probably guess, later.