Here are some original old school D&D modules that should be easy to find and not cost you an arm or a leg if you buy them online:
I1 The Forbidden City (TSR, 1980): Old school AD&D sandbox setting in a "lost" jungle city inhabited by snakemen (yuan ti), frogmen (bullywugs), and lots of other weird and dangerous creatures. Lots of room for development here and no two adventures will play alike (due to multiple adventure paths and foes).
B4 The Lost City (TSR): This old school original D&D module consists of a pyramid buried in the desert sands which holds various degenerate groups battling each other for control of the underground empire.
X1 Isle of Dread (TSR): Lost island sandbox setting with lots of different adventure ideas
WG4 Lost Temple of Tharizdun (TSR): written by the master himself, EGG, this AD&D adventure takes place in a long abandoned temple to a dark god hidden in a mountain valley. Initial conflict is against monsters who now inhabit the structure, but if the party delves deep enough they will run into Things Best Left Undisturbed.....!
Axe of the Dwarvish Lords (TSR): This AD&D supermodule written in the 90s takes place in an long abandoned Dwarvish citadel now inhabited by an army of goblins.
Gates of Firestorm Peak (TSR): This 90s AD&D module takes place in a weird, otherworldly mountain that has connections to a "Far Realm" of madness and insanity. Sounds like it would fit right in with Raggi's stuff!
Not as easy to acquire are the classic Judges Guild modules Caverns of Thracia and Dark Tower (however, the 3.5 reprints should be a lot easier to find and are backwards compatible). Both are great and concern ancient, underground empires with lots of evil things lurking about.
Well, for starters, I'd say don't use D&D. It is a game tailored towards violent conflicts, which is exactly what you're avoiding, it seems. Mind you, I said "violent conflicts". No story, thus no game, can exist without any conflict whatsoever. I'm not also saying it's completely undoable with D&D, just mainly... a waste of its design and practical goals. Another way to put it, to use a metaphor, is: smartphones are great, you can do a lot with them, they're like handheld computers... But they can't really substitute a desktop computer in every way, maybe not even most ways.
Now, if you're willing to work outside of D&D, there are some good systems out there for that "action and adventure doesn't mean swinging swords all the time" vibe you're after, like, for example, Fate (The Dresden Files RPG, Spirit of the Century, Diaspora, etc), in which most of the mechanics about resolving conflicts are the same, regardless if it's a brawl, a wardrobe and style show off or even an economic dispute between Lex Luthor and Bruce Wayne. It's worth a look, really, and there are SRDs available for some of those games (Spirit of the Century and Diaspora, iirc).
If you're sticking to D&D, plotting the campaign isn't the difficult part; the difficult part is to design encounters (which is just a way of saying "conflict scene") that allow your PCs to shine doing their thing when most of their sheets are geared towards combat (yeah, players do that, it being the game it is).
For the wizard (most hocus-pocus folks, really) and rogue, that's easy. Most other types, though, will rely purely on RP, most of the time, which isn't bad per se, just kinda unfair, since some players get to look at their sheets and say "I can do this, this and that", while the fighter's player has to memorize lines from Gladiator and the ranger's player has to become a living Bear Grylls encyclopedia.
If your group can pull it off, that campaign'd be the stuff of legends, but it'll be hard, really.
Best Answer
Doesn't get more detailed than this. Necromancer Games Mother of all encounter tables.