Note that I'm looking for recommendations that people have actually played, or at least read. It's easy enough to do a search on DMsGuild, but I find most of that stuff doesn't appeal to me. I would rather not spend money without a better idea of what I'm paying for.
I'm not really looking for something combat heavy - my players aren't really very good at tactics. After something more mythic/mysterious.
Yes, in fact the original tomb is used as a portion of the adventure itself (the boxed set included a direct reprint of the original module). I'd use the toned-down 5th edition version; I think the module would work better with that instead of the frequently-unfair original (as you definitely want the party to survive to get to Moil and the Fortress of Conclusion.
I am going to be running a game for my coworkers and am thinking of lost mine of phandelver --> storm king's thunder and then who knows what if we make it that far, so I am interested in what people contribute to this thread.