Just a couple quick notes on other peoples' posts. At Swords of Minaria there's an intriguing concept: micro-megadungeons. Basically, just the minimum needed to get characters up and running to hit 4th level as quickly as possible. There is a problem with this, however: although it does use the gold standard of experience, (exemplified in another post today at The Mule Abides,) it's clearly designed with at least a partial focus on combat, since it's calculated with half the experience to be earned from defeating monsters. Even if, like me, you assume "defeat" does not equal "kill", that still requires the adventures to make contact with each and every creature in the dungeon. Also, I think that the post assumes that experience points are not divided between adventurers: if the party finds one gold piece, everyone gets one XP; if the party kills one skeletone, everyone gets 100 XP.
If you want to make up the difference between the XP assumed in the post and XP likely to be earned if treasure is evenly divided and some monsters avoided, consider XP awards for solving problems.