My family is not at all religious, and I invariably don't observe the dietary part of Passover (Oops, pasta. Oops, bagels. Oops, pizza...), but the seder is my favorite Jewish ritual.
Growing up, we glossed quickly over the ceremony and got right to the matzo ball soup, brisket and other goodies coming out of Nana's kitchen. Nana died in 2000 at age 93 without passing on her matzo ball recipe, but my great-aunt believes the secret was seltzer and fresh schmaltz.
Over tenth grade spring vacation, my sister and I went to Puerto Rico with Nana and Papa, and there I attended my first "real" seder, a large community event at the El San Juan hotel (I know, that's redundant). Who knew there was so much AFTER the meal? Although we didn't know most of the songs, the repetitive "12 Days of Christmas"-type lyrics made them easy to learn. Speaking of Christmas, that scary moment when the door is opened for Elijah seems to be the Jewish equivalent of being scared to go downstairs Christmas Eve lest you run into Santa. To this day my sister is scared of Santa, but that's another story.
I went to another community seder a few years later at my relatives' reform temple on Long Island. They used a beautiful Haggadah with sheet music and everything written out phonetically, and I got a copy of my own. Two copies, actually.
I was able to refer to this Haggadah the one time I hosted a seder in the '70s. Well, not really hosted since a co-worker from Ohio came early to cook, and led the service. We were just 3 (including his cousin), but left nothing out, and I got to keep the leftover charoseth (yum). The following year, we did it again at his cousin's, with a few more attendees.
Then there was the time a friend's somewhat religious family surprised me by doing part of the reading in fake Southern accents, and the time another friend's wannabe rabbi boyfriend prolonged things by adding extensive commentary (PLEASE, we're hungry!). And the year the host was on a very strict diet, so we not only had grape juice (which I always drink anyway) instead of wine, but no matzo!
And our own family traditions, with my great-uncle always hiding the afikoman in a picture frame, and my cousin decrying rote reading and giving her own explanation. And the realization that the uh, binding nature of matzo led to the expression, "Let my people go!"
My favorite Passover moment is one I wasn't even there for: when, as a little kid, my older nephew asked the then-very-elderly Nana if she was a slave in Egypt. Perfect logic.