@Featherkin Varied layouts, but aiming for nonlinear where possible. Highmaul layout resembles Firelands; Blackrock Foundry more like ICC.- Watcher (@WatcherDev) February 12, 2014
We can see the map for Blackrock Foundry above, and understand what Watcher means with regard to the ICC-esque layout. The circular room at the top is likely to be the room you're looking to unlock by completing wings. And a Firelands-ish layout has much the same effect on raiders. While the world first progression guilds will dislike it, as they thrive on assessing who's behind and who's ahead in the race, they're a tiny percentage of the total raiding playerbase. For the rest of us, it's incredibly frustrating to get stuck on a boss, for whatever reason, and feel like there's nothing you can do but repeatedly throw yourselves at that same encounter.
That's where raids like the Mists ones have been difficult, they've all been very linear, and it means that the difficulty curve has to be incredibly smooth so that players can progress. The targeted nerfs we've seen in Throne of Thunder and more recently Siege of Orgrimmar have indicated the importance of this tuning. Of course, the first tier of Mists you had several raids you could be doing, albeit with completion of one required to progress into the next. This is another option, rather better executed in the first tier of Cataclysm. That one tier was fantastic, three raids of different sizes, layouts and designs. If they can pull that off with Warlords for more than just one tier, it'll be great news for raiders everywhere.
My only concern is the "wherever possible". Watcher has said before that they never wanted to have such linear content in Siege of Orgrimmar, but that the story just drove them that way. They wanted to have the feeling of players going deeper and deeper into Garrosh's lair, and finding new and terrible things as they did. That didn't work well in a non-linear raid. I feel, personally, like they could have done it somehow, even if the story didn't invite it. But, that is indicative of my personal preferences. Do you prefer linear or non-linear content?