>>"Once we find and kill the RttTOEE Final Boss, I think we'll need a break from vast, overarching, world-ending megaplots for a while. And after spending so much time grovelling through the crater mines, we're not too excited about another generic dungeon crawl."
I totally hear you. And while I think some folks wrote some good suggestions of great adventures, I don't think an Adventure Path or Red Hand fo Doom (both a vast, overarching, megaplot) is what you're looking for.
Pull out your pocketbook and do a little ordering from your OFLGS (online friendly local game store):
Necromancer Games has "A Lamentation of Thieves". It's adventures with an overlying plot, BUT they are spaced out in levels, allowing you to run stuff in between and tell your own stories, but have a thread there in the background to tie them together as you see fit. See also Goodman Games' DCC #14, "Dungeon Interludes" which is along the sames lines: "6 nonconsecutive interconnected adventures that slowly uncover a common threat". these both allow you run your own stuff, and then toss in a thread to give the campaign some continuity without the big, overall megaplot.
Second, here's some adventures not over-loaded with dungeon crawl stuff: Necromancer Games' Vault fo Larin Karr, Hall of the Rainbow Mage, and/or What Evil Lurks. I mean, they all have dungeons, but they are not the sole focus of the adventuring.
Or, with the two storyarch adventures above get a few recent copies of Dungeon Magazine and be enlightened to a DM's best friend!
-DM Jeff