I found many BECMI adventures were really good, especially at higher levels with the M series. While several of them are a bit railroady, they're often quite fun. The Maelstrom is a space faring version of The Odyssey, where the players have to face many of the same trials (powered up for epic tier, of course). I used it with Vengance of Alphax and Twilight Calling to create an epic end to a high level AD&D campaign. Five Coins for a Kingdom was goofy, but also a blast if you don't pry apart the premise. The Endless Stair also has a ridiculous start, but ends extremely well.
For AD&D, Isle of the Ape is fantastic, giving the perfect King Kong/lost jungle vibe. A Sword for a Hero from Treasures of Greyhawk was pretty good, but not my favorite. To Hell and Back from Tales of the Outer Planes and the Dragon Mountain boxed set aren't quite "epic tier," but can be done in such a way to challenge such characters.
For AD&D, Isle of the Ape is fantastic, giving the perfect King Kong/lost jungle vibe. A Sword for a Hero from Treasures of Greyhawk was pretty good, but not my favorite. To Hell and Back from Tales of the Outer Planes and the Dragon Mountain boxed set aren't quite "epic tier," but can be done in such a way to challenge such characters.