Navigating long straight hallways from cutscene to cutscene

What game am I referencing with this post's title?  Tell you later.

This post is all about the actual level design in RPGs, and in many cases it is rather horrific.  It's horrific because it's uninteresting, uninspired, and generally just not enjoyable to walk around.  My goal is to avoid this problem, but first lets discuss a few games that have poor level design and good level design.  Feel free to leave your own suggestions and why in the comments.

Final Fantasy XIII and X

Notorious for the main game being almost a single corridor with lots of pretty graphics on the sidelines, both of these games have extremely poor level design.  There is nothing interesting or fun about walking down a straight line.  Now FFXIII and X happen to be two of my favorite final fantasies and that's due to a variety of other factors.  I actually enjoyed that the stories did not require running around to pick up random items in order to move the story along, nor side quests that were required to progress.  However, some puzzles, which FFX did have with its cloisters of trials, and some interesting twists/turns or other sorts of areas to explore would have allowed these games to be more interesting to move through instead of just holding up until a cut scene or an encounter.  Again, X was not as bad as XIII with this problem.

A good examples:

Etrian Odyssey 3 Stratum 4,

Very specific, I know.  Stratum 4 of EO3 had a few really interesting things going for it.  First, it introduced a new mechanic, the gateway door.  If you went through a gateway door the wrong way, all gateway doors on the floor would close.  These could be opened with a nearby switch.  The game first introduces these doors to you under circumstances that show both how they work, it's a room with 2 gateway doors that lead in, how to open them, and then right afterward it demonstrates a second way they will be used.

When you leave the first room with these doors, you notice a FOE (also known as a wandering miniboss) infront of you, however, as soon as you step towards it, the gateway door out of the first room closes, and the FOE is kept safely locked away.  The nearest switch to undo this is a few rooms away, so you cannot accidentally open the door and fight the foe; you have to intentionally go back for it.  This is a neat way to introduce a mechanic, and then the rest of the area plays with the mechanic in different ways.  By the time the player is sick of dealing with these doors, the game moves on to a new feature.  I consider that to be a good way to break up wandering through corridors.

What games have impressed you with their design?  I'm not just talking aesthetics here, which FFXIII has in spades, but in more interesting mechanics on the over world or in the dungeon itself.