I started out in 4e being very delve neutral, leaning toward very short dungeons of 2-4 encounters, literally an entrance encounter, something to set the tone, and then a boss or bosses. Most interesting was my second ever, which featured three dragons in a standoff over "wyrmbirth cavern" and are too scared of the others to make a move, but want to use the PCs to break the stalemate. But most of the game was outside a dungeon context for us. Even my college underdark game wasn't actually dungeon structured.
But now? I'm obsessed with them: jacquayed structures, treasure hunting instead of plot drive, less linearity, mythic atmosphere, puzzles in the zelda tradition, secret passages, environmental storytelling, plenty of fun combat, character driven stories pressured by the dungeon, meaningful problem solving differences between character builds.
Ive been all about learning to make real, high quality dungeons lately.