I’ve been thinking a lot about what adventure to run as the “High Level” adventure for the campaign. High level, as a tier, has fluctuated from edition to edition. In Basic D&D, characters could go as high as level 36 (and beyond if you take Immortals into account). AD&D had no theoretical upper limit, but game play didn’t seem to change much once you go into the teens. 3.X/Pathfinder, of course, got into high level play in the mid-teens and Epic level play was always spotty (and not officially supported in Pathfinder). 4E separates things out explicitly, making the divisions between low (Heroic), mid (Paragon), and high (Epic) obvious.
Couple that with my new approach which has me running only certain parts of a series per edition (i.e. U1: Sinister Secret of Saltmarsh started for Basic Low Level and got switched to X1: Isle of Dread due to PC derailment, U1 will be repeated for AD&D low level, U2 will come in Pathfinder low level, and U3 for 4E low level; I3: Pharaoh is Basic D&D mid-level, I4 AD&D mid-level, and so forth).
Of course, there will be some repetition since most series are 3 adventures and I have 4 editions to run (so far), or I might throw a 4th or 5th adventure into the mix.
High level is the real problem. There just aren’t that many adventures that I own for high-level play. Most cap out right at the low teens. The C & M series adventure written for basic D&D for characters in their 20s and 30s are reasonably inexpensive, but there isn’t really a series, per se. Plus, the domain-running/building aspects of high-level Basic D&D play are something I don’t think a majority of my players would enjoy (based on the amount of bitching I heard regarding the wilderness exploration portion of X1, i.e. the parts where they weren’t killing things and taking their stuff or even interacting with NPCs).a
The only way I could run the same adventure 4 times with little-to-no repetition would be to run S1: The Tomb of Horrors as the high-level adventure. In Basic D&D and AD&D, they would probably die very quickly. I could run it until there is a TPK, then make the switch to a new edition. By the time Pathfinder rolls around, most of the insta-kill traps aren’t insta-kill anymore due to the way the system works, but they still might die somewhere before the end. If they, at any point, solve the puzzles and make it to the end, I would have to run a different high-level adventure. Perhaps Q1: Queen of the Demonweb Pits?