I'd recommend B4 The Lost City. I'm not a fan of the Pharoah/Oasis/Tomb series.
You stole my answer!
But I like I4-I6 too with a DM who knows how to redesign them into workable modules.
It's hard to understand what Mr. OP is asking for. Are you talking about a desert-based environment specifically affecting the strategies of the NPCs? Perhaps you could tell us what counts and isn't just another underground dungeon in a desert?
I would think you could take any above ground adventure and place it into the desert with the appropriate modifications. B2 with lizardfolk of different species /varieties. I6 with the castle re-mapped as a Persian palace enshrouded by sandstorms and the barge and town people as nomads by an oasis.
It's much easier changing the environment than rewriting an entire adventure.
You stole my answer!
But I like I4-I6 too with a DM who knows how to redesign them into workable modules.