Such as? I can think of a few places where I'd like to have content like that, but I don't think they necessarily require a first visit to those locations. I think 'In Their Absence' proved that we can put group content in older areas pretty successfully.
MoL
Given what we saw in ToO, wouldn't it be possible for Saruman to have had some of the more hazardous experiments off-site?
A break in and termination of that lab and Saruman's experiments would have formed an interesting instance cluster of the ITA style for HD. What would have made it better was the other NPCs recognizing that we're excellent for this type of work because of the reputation we have because of all the stuff we've done in Rohan.
Another possible instance cluster with DA would involve us hopping through a set of instances, going ship to ship, fighting off a corsair advance on one of the bigger galleons, with the "instance" being scripted as we take hold of a galleon then throw the entire corsair naval formation into chaos by having a ship firing on friendly targets, then hopping from ship to ship.
Or you could create a story with the instance clusters where we have four three mans, which have various teams, then those funnel into two six man isntances, with each of the three man instances merging with exactly one other, then have a twelve man as the capstone for it where it ties the story together. For example, using this as a series of maneuvers in a larger battle (like what could have been done with Helm's Deep), that's a mix of encounters/scripted instances. Or something like this can be done at the Black Gate, as that would help make it feel more epic, and also allow exploration of multiple story paths through the encounter, which can make the experience all the more richer for us.
Part of the raid issue deals with this notion that all instances have to be in indoor dungeons, or outdoors encounters. Very few take advantage of the scripting to cause possible movement, especially if you have a wall of death behind you, like OD Wound wing, to keep the players advancing at a minimum rate, while also doubling as a weed out mechanic, because if the players can't get through the "gauntlet", then they aren't going to beat the boss.
There plenty of places and tactics you can take with creating a raid encounter to make it fit the area, but part of it requires divorcing yourself from the pattern of trash => boss for four wings, followed by a mini-boss before the final boss, which has basically been the pattern for the majority of the raid instances.