Dayenu means "it would have been enough."  And not in a kvetchy/sarcastic way!  Dayenu is a sincere expression of gratitude, of the Jewish people's cup overfloweth. 

There are many any verses in the Hebrew proclaiming how it would have been enough just to be brought out from slavery in Egpyt, to get the Torah, to be gifted Shabbat, etc...

In this version, you may sing some, all or none of the traditional verses, but then open it up so Dayenu can become a participatory song where everyone offers their own "dayenu" for the year. As in: It would have been enough if________, but also ______! Dayenu! Day-day-enu...etc...

For example:It would have been enough if I graduated high school this year, but I also got accepted to my top choice for college! Dayenu! (And everyone sings the chorus!)

This an be done at the Dayenu moment in the Seder or introduced earlier and then whenever someone is moved throughout the Seder to share their Dayenu moment, they can. Depends on the enthusiasm of the crowd.