I've just reached the point in Dragon Quest IX where I can start exploring the Treasure Map dungeons, and I completed the one that the game gives you as a "starter".
It appears that the floors are (semi?) random, and can be fairly large, so I just wanted to check if there was any point in fully exploring each floor, or if I should go down as soon as I find the stairs to the next level. I did run into one blue chest, but the contents of those are never very good, so those aren't particularly exciting. Is there anything more significant to find, or is it best to just reach the boss as quickly as possible?