Coming back a bit to another part of the thread, more RP in the adventures and books, I think that Demon Queen's Enclave it's awesome.
Lots of RP moments, and the skill challenges are very cool. The best part is that you can do things with attack rolls or skill rolls

.
I mean, there are encounters that can be done talking or fighting. And there's no downside to any of them. Sometimes the players feel that if they don't kill the bad guys the "lose" some loot. It's like "okey, we avoided that dude, but man, look how shiny is that mace... sniff". But in Demon Queen's that doesn't happen (much). And that's cool, you choose a path to play in your game and you shouldn't be "punished" for it for no special reason.
Perhaps now that the first module series is coming to an end, the next one could be centered in the Feywild. This one is clearly 100% Shadowfell (and that's perfect), but if the next adventures are going to be so Shadowfellian (that's not even a word!

) people will end being tired of it.
And the Feywild has an awesome chance of TONS of RP situations. Reading the Manual of the Planes you find things like the Court of Stars, the Summer Fey, Green Fey, Winter Fey, etc. that could provide a really good background for a serie of adventures.
For example, it could start in the material plane, with a town where the people doesn't have dreams. Yeah, they sleep, but they don't dream. The PCs discover there's some kind of evil cult that steals that "dream energy". Later they discover that creatures of the Plane of Dreams (another good idea of the Manual of the Planes) are attacking the Feywild. And the players have to fight against those nightmares, they have to go to the court of stars (the city that stays 6 months here and 6 months there it's also a perfect place for some adventures), make pacts with feys, fight in battles and in the end a demon prince, the Prince of Nightmares is the mastermind behind all of it. That's only an idea, but the Feywild has more RP options than the Shadowfell (I think). And that way the artists can use some other colors

I'm sure they are a bit bored of all that grey, sick green, brown and black of the Shadowfell.