It has taken me WAY too long to get back to this and for that I apologize!
I agree that the decision-making part of the process is the biggest issue in dungeons. One option is definitely to just reduce the choices that have to be made, either by automating them (The group will always go left!) or by just removing the pointless fluff from the dungeon (why spend a week dealing with an empty room that the players search over).
I think that Len makes a good case for pre-deciding the actions that party will take. Don't bother waiting for the wizard to tell you for the fifth time that he's going to detect magic on the room or for the rogue to tell you he's checking for traps. Just do it for them and move on.
The "Gardens of Ynn" approach is definitely one way to do it, but I worry, like CancerMan said, that it takes away from the experience of dungeon-crawling. I think it would probably work find for smaller dungeons, but for a mega dungeon, it might be lacking the exploration experience.
OOC:I'll put in more thoughts later on, but this is as far as I got with this sit-down