When entering a quest, it would be very helpful to know up-front the minimum number of party members needed to complete it. By this I don't mean a subjective gauge of how "tough" a quest will be, but rather, whether the designers of the quest chose to include elements like simultaneously flipped levers that can't be done without a certain number of party members. A fair number of new DDO entrants have complained about not being told in advance that a quest they've spent an hour plowing through actually can't be done with the current party size, and I don't see why a game that's supposedly trying to become more small/solo-friendly can't add this information to the screen you see when entering a quest.
Granted, quests that "need" a certain number of party members can sometimes be done with less if you get lucky with web spells (I'm thinking of the burning heart tomb here) or have the proper speed/jump boosts (say, the Pit). So in this case a "minimum" party size wouldn't necessarily reflect what an experienced DDO gamer can accomplish -- but then again, that kind of gamer isn't going to be reading the quest entry window anyway.
So that's my suggestion: a minimum party size field on the quest entry screen.